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Colloquia History

ics Colloquium
Friday, October 18, 2019
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, October 11, 2019
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, October 4, 2019
3:30 PM
Physics Building, Room 204
Professor Xiaoyang Zhu [Host: Seunghun Lee]
Columbia University
"Ferroelectric Polarons, Belgian Waffles, and Principles for “Perfect” Semiconductors"
ABSTRACT:

Lead halide perovskites have been demonstrated as high performance materials in solar cells and light-emitting devices. These materials are characterized by coherent band transport expected from crystalline semiconductors, but dielectric responses and phonon dynamics typical of liquids.  Here we explain the essential physics in this class of materials based on their dielectric functions and dynamic symmetry breaking on nano scales. We show that the dielectric function in the THz region may lead to dynamic and local ordering of polar nano domains by an extra electron or hole, resulting a quasiparticle which we call a ferroelectric large polaron, a concept similar to solvation in chemistry. Compared to a conventional large polaron, the collective nature of polarization in a ferroelectric large polaron may give rise to order(s)-of-magnitude larger reduction in the Coulomb potential. We show that the shape of a ferroelectric polaron resemble that of a Belgian waffle. Using two-dimensional coherent phonon spectroscopy, we directly probe the energetics and local phonon responses of the ferroelectric large polarons. We find that that electric field from a nascent e-h pair drives the local transition to a hidden ferroelectric order on picosecond time scale.  The ferroelectric or Belgian waffle polarons may explain the defect tolerance and low recombination rates of charge carriers in lead halide perovskites, as well as providing a design principle of the “perfect” semiconductor for optoelectronics.

ics Colloquium
Friday, September 27, 2019
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, September 20, 2019
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, September 13, 2019
3:30 PM
Physics Building, Room 204
Israel Klich [Host: Bob Jones]
University of Virginia - Physics
"Quantum states, walks, tiles, and tensor networks"
ABSTRACT:

A major challenge of physics is the complexity of many-body systems. While true for classical systems, the difficulty is exasperated in quantum systems, due to entanglement between system components and thus the need to keep track of an exponentially large number of parameters. In particular, this complexity places a challenge to numerical methods such as quantum Monte Carlo and tensor networks. Here, exactly solvable models are of crucial importance:  we use these to test numerical procedures, to develop intuition, and as a starting point for approximations.

In this talk, I will explain our current understanding of a new solvable "walk" model, the area deformed Motzkin model. The model shows that entanglement may be more acute than previously thought, in particular, it features a novel quantum phase transition between a non-entangled phase and extensively entangled “rainbow” phase. Most remarkably, the model motivated the construction of a new tensor network, providing, after many years, the first example for an exact tensor network description of a critical system. Finally, I will remark on open problems, and on exciting connections to other fields such as the notion of holography in field theory, and a famous problem in non-equilibrium statistical mechanics.

ics Colloquium
Friday, September 6, 2019
2:30 PM
Physics Building, Room 204
Professor Or Hen [Host: Nilanga Liyanage]
MIT - Massachusetts Institute of Technology
"Neutron stars droplets and the quarks within"
ABSTRACT:

Neutron stars are one of the densest strongly-interacting many-body systems in our universe. A main challenge in describing the structure and dynamics of neutron stars steams from our limited understanding of the nuclear interaction at high-densities (i.e. short-distances) and its relation to the underlaying quark-gluon substructure of nuclei.

In this talk I will present new results from high-energy electron scattering experiments that probe the short-ranged part of the nuclear interaction via the hard breakup of Short-Range Correlations (SRC) nucleon pairs. As the latter reach densities comparable to those existing in the outer core of neutron stars, they represent ’neutron stars droplets’ who’s study can shed new light to the dynamical structure of neutron stars. Special emphasis will be given to the effect of SRCs to the behavior of protons in neutron-rich nuclear systems and how it can impact the cooling rates and equation of state of neutron stars.  Pursuing a more fundamental understanding of such interactions, I will present new measurements of the internal quark-gluon sub-structure of nucleons and show how its modification in the nuclear medium relates to SRC pairs and short-ranged nuclear interactions. 

Given time I will also discuss the development of new effective theories for describing short-ranged correlations, the way in which they relate to experimental observables, and the emerging universality of short-distance and high-momentum physics in nuclear systems.

ics Colloquium
Friday, August 30, 2019
3:30 PM
Physics Building, Room 204
Jeffrey Teo [Host: Bob Jones]
University of Virginia - Physics
"From interacting Majorana to universal fractional quasiparticles"
ABSTRACT:

Ising anyons, Majorana fermions (MF) and zero energy Majorana bound states have promising prospects in topological quantum computing (TQC) because of their ability to store quantum states non-locally in space and insensitivity to local decoherence. Unfortunately, these objects are not powerful enough to assemble a TQC that can perform universal operations using topological braiding operations alone. On the other hand, there are anyonic quasiparticles, like the Fibonacci anyon in a Read-Rezayi quantum Hall state, that are universal in the braiding-based TQC sense. However, these are quantum dynamical excitations, which can be challenging to spatially manipulate and susceptible to temperature fluctuations in a thermodynamic system. We propose and define a new notion of universal fractional quasiparticles, which are semi-classical static topological defects, supported by many-body interacting MFs in a superconducting spin-orbit coupled topological electronic system.

ics Joint Colloquium with Physics and Astronomy/NRAO


Friday, April 26, 2019
3:30 PM
Physics Building, Room 204
Andrew Steiner [Host: Kent Yagi]
University of Tennessee
"From Multimessenger Astronomy to Neutrons and Protons"
ABSTRACT:

Of course, multimessenger astronomy promises to revolutionize

astronomy and our understanding of nucleosynthesis. My

research shows that it goes further: astronomical observations

(via both photons and gravitational waves) provides a unique

laboratory to deepen our understanding of QCD and the

nucleon-nucleon interaction. Most current work is focused

on the equation of state. While the equation of state is

indeed important, in this talk, I show how we can

go beyond energy density and pressure. I present the first

large-scale Bayesian inference of neutron star observations

and nuclear structure data to obtain novel results on the

composition of dense matter and the nature of nucleonic

superfluidity.

ics Colloquium
Friday, April 19, 2019
3:30 PM
Physics Building, Room 204
Dr. Craig D. Roberts [Host: Nilanga Liyanage]
Argonne National Laboratory
"Emergence of Mass in the Standard Model"
ABSTRACT:

Quantum Chromodynamics (QCD), the nuclear physics part of the Standard Model, is the first theory to demand that science fully resolve the conflicts generated by joining relativity and quantum mechanics.  Hence in attempting to match QCD with Nature, it is necessary to confront the innumerable complexities of strong, nonlinear dynamics in relativistic quantum field theory.  The peculiarities of QCD ensure that it is also the only known fundamental theory with the capacity to sustain massless elementary degrees-of-freedom, gluons (gauge bosons) and quarks (matter fields); and yet gluons and quarks are predicted to acquire mass dynamically so that the only massless systems in QCD are its composite Nambu-Goldstone bosons.  All other everyday bound states possess nuclear-size masses, far in excess of anything that can directly be tied to the Higgs boson.  These points highlight the most important unsolved questions within the Standard Model, namely: what is the source of the mass for the vast bulk of visible matter in the Universe and how is this mass distributed within hadrons?  This presentation will provide a contemporary sketch of the strong-QCD landscape and insights that may help in answering these questions.

 

ics Colloquium
Friday, April 12, 2019
3:30 PM
Physics Building, Room 204
Dr. Vivek Goyal [Host: MIller Eaton]
Boston University
"Computing Images from Weak Optical Signals"
ABSTRACT:

In conventional imaging systems, the results are poor unless there is a physical mechanism for producing a sharp image with high signal-to-noise ratio.  In this talk, I will present two settings where computational methods enable imaging from very weak signals:  range imaging and non-line-of-sight (NLOS) imaging.

Lidar systems use single-photon detectors to enable long-range reflectivity and depth imaging.  By exploiting an inhomogeneous Poisson process observation model and the typical structure of natural scenes, first-photon imaging demonstrates the possibility of accurate lidar with only 1 detected photon per pixel, where half of the detections are due to (uninformative) ambient light.  I will explain the simple ideas behind first-photon imaging and lightly touch upon related subsequent works that mitigate the limitations of detector arrays, withstand 25-times more ambient light, allow for unknown ambient light levels, and capture multiple depths per pixel.

NLOS imaging has been an active research area for almost a decade, and remarkable results have been achieved with pulsed lasers and single-photon detectors.  Our work shows that NLOS imaging is possible using only an ordinary digital camera.  When light reaches a matte wall, it is scattered in all directions.  Thus, to use a matte wall as if it were a mirror requires some mechanism for regaining the one-to-one spatial correspondences lost from the scattering.  Our method is based on the separation of light paths created by occlusions and results in relatively simple computational algorithms.

Related paper DOIs:
10.1126/science.1246775
10.1109/TSP.2015.2453093
10.1109/LSP.2015.2475274
10.1364/OE.24.001873
10.1038/ncomms12046
10.1109/TSP.2017.2706028
10.1038/s41586-018-0868-6

ics Colloquium
Friday, April 5, 2019
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, March 29, 2019
3:30 PM
Physics Building, Room 204
Dr. Ho Nyung Lee [Host: Seunghun Lee]
Oak Ridge National Laboratory
"Interfaces in oxide quantum heterostructures"
ABSTRACT:

Complex oxides are known to possess the full spectrum of fascinating properties, including magnetism, colossal magneto-resistance, superconductivity, ferroelectricity, pyroelectricity, piezoelectricity, multiferroicity, ionic conductivity, and more. This breadth of remarkable properties is the consequence of strong coupling between charge, spin, orbital, and lattice symmetry. Spurred by recent advances in the synthesis of such artificial materials at the atomic scale, the physics of oxide heterostructures containing atomically smooth layers of such correlated electron materials with abrupt interfaces is a rapidly growing area. Thus, we have established a growth technique to control complex oxides at the level of unit cell thickness by pulsed laser epitaxy. The atomic-scale growth control enables to assemble the building blocks to a functional system in a programmable manner, yielding many intriguing physical properties that cannot be found in bulk counterparts. In this talk, examples of artificially designed, functional oxide heterostructures will be presented, highlighting the importance of heterostructuring, interfacing, and straining. The main topics include (1) charge transfer induced interfacial magnetism and topologically non-trivial spin textures in SrIrO3-based heterostructures and (2) lattice and chemical potential control of oxygen stability and associated electronic and magnetic properties in nickelate-and cobaltite-based heterostructures.

This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.

ics Colloquium
Friday, March 22, 2019
3:30 PM
Physics Building, Room 204
Jim Gates, Ph.D. [Host: Diana Vaman]
Brown University
"A Mathematical Journey Thru SUSY, Error-Correcting Codes, Evolution, and a Sustainable Reality "
ABSTRACT:

This presentation describes an arc in mathematical/theoretical physics traversing concepts from equations, graphs, error-correction, and pointing toward an evolution-like process acting on the  mathematical laws that sustain reality.

ics Colloquium
Friday, March 8, 2019
3:30 PM
Physics Building, Room 204

"Available"
ics Colloquium
Friday, March 1, 2019
3:30 PM
Physics Building, Room 204
Genya Kolomeisky [Host: Israel Klich]
University of Virginia - Physics
"Kelvin-Froude wake patterns of a traveling pressure disturbance"
ABSTRACT:

Water wave patterns behind ships fuel human curiosity because they are both beautiful and easily observed.  These patterns called wakes were famously described in 1887 by Lord Kelvin.  According to Kelvin, the feather-like appearance of the wake is universal and the entire wake is confined within a 39 degree angle.  While such wakes have been observed, deviations from Kelvin’s predictions have also been reported.  In this talk summarizing my work with UVA alumnus Jonathan Colen I will present a quantitative reasoning based on classical surface water wave theory that explains why some wakes are similar to Kelvin’s prediction, and why others are less so.  The central result is a classification of wake patterns which all can be understood in terms of the problem originally treated by Kelvin.

ics Colloquium
Thursday, February 28, 2019
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, February 22, 2019
3:30 PM
Physics Building, Room 204
Reserved [Host: Diana Vaman]
ics Special Colloquium


Wednesday, February 20, 2019
3:30 PM
Physics Building, Room 204
David Nichols [Host: Diana Vaman]
University of Amsterdam
"Gravitational waves and fundamental properties of matter and spacetime"
ABSTRACT:

Gravitational waves from the mergers of ten binary black holes and one binary neutron star were detected in the first two observing runs by the Advanced LIGO and Virgo detectors. In this talk, I will discuss the eleven gravitational-wave detections and the electromagnetic observations that accompanied the neutron-star merger. These detections confirmed many of the predictions of general relativity, and they initiated the observational study of strongly curved, dynamical spacetimes and their highly luminous gravitational waves. One aspect of these high gravitational-wave luminosities that LIGO and Virgo will be able to measure is the gravitational-wave memory effect: a lasting change in the gravitational-wave strain produced by energy radiated in gravitational waves. I will describe how this effect is related to symmetries and conserved quantities of spacetime, how the memory effect can be measured with LIGO and Virgo, and how new types of memory effects have been recently predicted. I will conclude by discussing the plans for the next generation of gravitational-wave detectors after LIGO and Virgo and the scientific capabilities of these new detectors. These facilities could detect millions of black-hole and neutron-star mergers per year, and they can provide insights on a range of topics from the population of short gamma-ray bursts to the presence of dark matter around black holes.

 

ics Colloquium
Friday, February 15, 2019
3:30 PM
Physics Building, Room 204
Reserved [Host: Diana Vaman]
ics Special Colloquium


Wednesday, February 13, 2019
3:30 PM
Physics Building, Room 204
Eliu Huerta [Host: Diana Vaman]
University of Illinois at Urbana-Champaign
"Frontiers in Multi-Messenger Astrophysics at the interface of gravitational wave astrophysics, large scale astronomical surveys and data science "
ABSTRACT:

The next decade promises fundamental new scientific insights and discoveries from Multi-Messenger Astrophysics, enabled through the convergence of large scale astronomical surveys, gravitational wave astrophysics, deep learning and large scale computing. In this talk I describe a Multi-Messenger Astrophysics science program, and highlight recent accomplishments at the interface of gravitational wave astrophysics, numerical relativity and deep learning. I discuss the convergence of this program with large scale astronomical surveys in the context of gravitational wave cosmology. Future research and development activities are discussed, including a vision to leverage data science initiatives at the University of Virginia to spearhead, maximize and accelerate discovery in the nascent field of Multi-Messenger Astrophysics.

 

ics Colloquium
Friday, February 8, 2019
3:30 PM
Physics Building, Room 204
Reserved [Host: Diana Vaman]
ics Colloquium
Thursday, February 7, 2019
3:30 PM
Physics Building, Room 204
Available
ics Special Colloquium


Wednesday, February 6, 2019
3:30 PM
Physics Building, Room 204
Robert Penna [Host: Diana Vaman]
Columbia University
"Black Hole Bridges"
ABSTRACT:

Black holes are bridges between astrophysics and fundamental physics.  I will describe three examples of this theme.  First, I will explain how contemporary theoretical ideas deriving from the holographic principle have proven useful for interpreting numerical simulations of electromagnetic outflows from spinning black holes.  These models are currently being tested against X-ray and radio observations of galactic black holes.  Second, I will describe a correspondence between black holes and lower dimensional fluids and discuss the possibility of probing this correspondence with gravitational wave memory experiments.  Finally, I will describe how gravitational wave observations of black hole tidal interactions might be used to find new symmetries acting on the event horizon.

ics Colloquium
Friday, February 1, 2019
3:30 PM
Physics Building, Room 204
Reserved [Host: Diana Vaman]
ics Special Colloquium


Wednesday, January 30, 2019
3:30 PM
Physics Building, Room 204
Jeremy Sakstein [Host: Diana Vaman]
University of Pennsylvania
"Testing Gravity with Cosmology and Astrophysics"
ABSTRACT:

We are entering a golden age of cosmology and astrophysics. In the coming decade we will have cosmological data for over a billion galaxies, a census of objects in the Milky Way, and a network of gravitational detectors spanning the globe that will detect thousands of events per year. This presents us with the unprecedented opportunity to learn how gravity behaves at the largest distances, and in the most extreme environments. In this talk I will describe how we can use current and upcoming data to understand the unexplained mysteries of the Universe, such as why the expansion of the Universe accelerating (dark energy). I will also discuss how to connect physics in these disparate regimes and how to test cosmology on small scales. To maximize the discovery potential of the data requires us to construct robust theoretical models, identify novel probes, and connect theory with observation, and I will describe projects where I have attempted to accomplish this. I will conclude the talk by discussing how this interdisciplinary effort will continue into the next decade and beyond.    

 

ics Colloquium
Friday, January 25, 2019
3:30 PM
Physics Building, Room 204
Available
ics Special Colloquium


Wednesday, January 23, 2019
3:30 PM
Physics Building, Room 204
Sarah Vigeland [Host: Diana Vaman]
University of Wisconsin Milwaukee
"Probing Massive and Supermassive Black Holes with Gravitational Waves"
ABSTRACT:

Observations have shown that nearly all galaxies harbor massive or supermassive black holes at their centers. Gravitational wave (GW) observations of these black holes will shed light on their growth and evolution, and the merger histories of galaxies. Massive and supermassive black holes are also ideal laboratories for studying strong-field gravity. Pulsar timing arrays (PTAs) are sensitive to GWs with frequencies ~1-100 nHz, and can detect GWs emitted by supermassive black hole binaries, which form when two galaxies merge. The Laser Interferometer Space Antenna (LISA) is a planned space-based GW detector that will be sensitive to GWs ~1-100 mHz, and it will see a variety of sources, including merging massive black hole binaries and extreme mass-ratio inspires (EMRIs), which consist of a small compact object falling into a massive black hole. I will discuss source modeling and detection techniques for LISA and PTAs, as well as present limits on nanohertz GWs from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration.

 

ics Colloquium
Friday, January 18, 2019
3:30 PM
Physics Building, Room 204
Markus Diefenthaler [Host: Simonetta Liuti]
Jefferson Lab
"The Electron Ion Collider Science "
ABSTRACT:

Quantum Chromodynamics (QCD), the theory of the strong interaction, is a cornerstone of the Standard Model of modern physics. It explains all nuclear matter as bound states of point-like fermions, known as quarks, and gauge bosons, known as gluons. The gluons bind not only quarks but also interact with themselves. Unlike with the more familiar atomic and molecular matter, the interactions and structures are inextricably mixed up, and the observed properties of nucleons and nuclei, such as mass and spin, emerge out of this complex system. To precisely image the quarks and gluons and their interactions and to explore the new QCD frontier of strong color fields in nuclei, the Nuclear Physics community proposes an US-based Electron Ion collider (EIC) with high-energy and high-luminosity, capable of a versatile range of beam energies, polarizations, and ion species. The community is convinced that the EIC is the right tool to understand how matter at its most fundamental level is made.

ics Special Colloquium


Thursday, January 17, 2019
3:30 PM
Physics Building, Room 204
Prem Kumar [Host: Bob Jones]
Northwestern University
"Quantum Engineering: A Transdisciplinary Vision"
ABSTRACT:

A global quantum revolution is currently underway based on the recognition that the subtler aspects of quantum physics known as superposition (wave-like aspect), measurement (particle-like aspect), and entanglement (inseparable link between the two aspects) are far from being merely intriguing curiosities, but can be transitioned into valuable, real-world technologies with performances that can far exceed those obtainable with classical technologies. The recent demonstration by the Chinese scientists of using a low-earth-orbit satellite to distribute entangled photons to two ground stations that are over a thousand kilometers apart is a stunning technological achievement—direct entanglement distribution over the best available fiber links is limited to a few hundred kilometers—and a harbinger of future possibilities for globally secure communications guaranteed by the power of quantum physics.

Harnessing the advantages enabled by superposition, measurement, and entanglement (SME)—the three pillars of quantum physics—for any given application is what is termed quantum engineering in general. In many instances, however, the details of the underlying science (high-temperature superconductivity, photosynthesis, avian navigation, are some examples) is still not fully understood, let alone how to turn the partially understood science into a potentially useful technology. Nevertheless, it has become clear in the last few decades that quantum engineering will require a truly concerted effort that will need to transcend the traditional disciplinary silos in order to create and sustain new breeds of science and technology communities that will be equally versed in quantum physics as they would be in their chosen area of technology. In this talk, I will present my vision for unleashing the potential of quantum engineering, taking some examples from ongoing and proposed research.

ics Special Colloquium


Wednesday, January 16, 2019
3:30 PM
Physics Building, Room 204
Stephen Taylor [Host: Diana Vaman ]
California Institute of Technology
"Frontiers of Multi-Messenger Black-Hole Physics"
ABSTRACT:

The bounty of gravitational-wave observations from LIGO and Virgo has opened up a new window onto the warped Universe, as well as a pathway to addressing many of the contemporary challenges of fundamental physics. I will discuss how catalogs of stellar-mass compact object mergers can probe the unknown physical processes of binary stellar evolution, and how these systems can be harnessed as standard distance markers (calibrated entirely by fundamental physics) to map the expansion history of the cosmos. The next gravitational-wave frontier will be opened within 3-6 years by pulsar-timing arrays, which have unique access to black-holes at the billion to ten-billion solar mass scale. The accretionary dynamics of supermassive black-hole binaries should yield several tell-tale signatures observable in upcoming synoptic time-domain surveys, as well as gravitational-wave signatures measurable by pulsar timing. Additionally, pulsar-timing arrays are currently placing compelling constraints on modified gravity theories, cosmic strings, and ultralight scalar-field dark matter. I will review my work on these challenges, as well as in the exciting broader arena of gravitational-wave astrophysics, and describe my vision for the next decade of discovery. 

ics Colloquium
Friday, December 7, 2018
3:30 PM
Physics Building, Room 204
Zohar Komargodski [Host: Marija Vucelja]
Stony Brook University
" Using Topology to Solve Strongly Coupled Quantum Field Theories"
ABSTRACT:

I will begin by describing an interacting model in Quantum Mechanics where exact results about the ground state can be established by using tools from topology. I will then argue that such tools are also useful for tackling interesting problems in Quantum Field Theory. In particular, I will review Yang-Mills theory and argue that using topology one can make several predictions about its possible phases. We will then also extend the considerations to Quantum Chromodynamics and discuss possible connections with particle physics phenomenology and with condensed matter physics.

ics Colloquium
Friday, November 30, 2018
3:30 PM
Physics Building, Room 204
Valery Nesvizhevsky [Host: Stefan Baessler]
Institut Laue Langevin, France
"A new approach to search for neutron-antineutron oscillations, and a couple of other phenomena based on neutron reflection from surface: gravitational and whispering-gallery quantum states of neutrons"
ABSTRACT:

“An observation of neutron-antineutron oscillations (n-n ̅), which violate both B and B — L conservation, would constitute a scientific discovery of fundamental importance to physics and cosmology. A stringent upper bound on its transition rate would make an important contribution to our understanding of the baryon asymmetry of the universe by eliminating the post-sphaleron baryogenesis scenario in the light quark sector. We show that one can design an experiment using slow neutrons that in principle can reach the required sensitivity of 1010 s in the oscillation time, an improvement of 104 in the oscillation probability relative to the existing limit for free neutrons. This can be achieved by allowing both the neutron and antineutron components of the developing superposition state to coherently reflect from mirrors. We present a quantitative analysis of this scenario and show that, for sufficiently small transverse momenta of n/n ̅ and for certain choices of nuclei for the n/n ̅ guide material, the relative phase shift of the n and n ̅ components upon reflection and the n ̅ annihilation rate can be small. While the reflection of n ̅ from surface looks exotic and counterintuitive and seems to contradict to the common sense, in fact it is fully analogous to the reflection of n from surface. The later phenomenon is well known and used in neutron research from its first years. We illustrate it with two selected example of gravitational and whispering-gallery quantum states of neutrons.”


[V.V. Nesvizhevsky, A.Yu. Voronin, Surprising Quantum Bounces, Imperial College Press, London, 2015]  

ics Colloquium
Friday, November 16, 2018
3:30 PM
Physics Building, Room 204
Mark Stiles [Host: Joe Poon & Avik Ghosh]
NIST
"Energy-efficient neuromorphic computing with magnetic tunnel junctions"
ABSTRACT:

Human brains can solve many problems with orders of magnitude more energy efficiency than traditional computers.  As the importance of such problems, like image, voice, and video recognition, increases, so does the drive to develop computers that approach the energy efficiency of the brain.  Magnetic devices, especially tunnel junctions, have several properties that make them attractive for such applications.  Their conductance depends on the state of the ferromagnets making it easy to read information that is stored in their magnetic state.  In addition, current can manipulate the magnetic state.  Based on this electrical control of the magnetic state, magnetic tunnel junctions are actively being developed for integration into CMOS integrated circuits to provide non-volatile memory.  This development makes it feasible to consider other geometries that have different properties.  I describe two of the computing primitives that have been constructed based on the different functionalities of magnetic tunnel junctions.  The first of these uses tunnel junctions in their superparamagnetic state as the basis for a population coding scheme.  The second uses them as non-linear oscillators in the first nanoscale “reservoir” for reservoir computing.

ics Colloquium
Friday, November 9, 2018
3:30 PM
Physics Building, Room 204
Marija Vucelja [Host: Bob Jones]
UVA-Physics
"Thermal relaxations, the Mpemba effect, and adaptation of bacteria "
ABSTRACT:

Most of my talk will be about anomalous thermal relaxations, such as the Mpemba effect. Towards the end of my talk, I will also highlight a few topics in population dynamics that I have been working on. 

 

The Mpemba effect is a phenomenon when "hot can cool faster than cold" - a “shortcut” in relaxation to thermal equilibrium. It occurs when a physical system initially prepared at a hot temperature, cools down faster than an identical system prepared at a colder temperature. The effect was discovered as a peculiarity of water. Despite following observations in granular gasses, magnetic alloys, and spin glasses, the effect is still most often referred to as an “oddity” of water, although it is widespread and general.  I will describe how to define a Mpemba effect for an arbitrary physical system, and show how to quantify and estimate the probability of the Mpemba effect on a few examples. 

 

In the remaining time, I will briefly talk about the adaptation of bacterial populations and the immune system of bacteria with CRISPR.  Besides being the biology's newest buzzword and favorite gene editing tool, CRISPR is also a mechanism that allows bacteria to defend adaptively against phages and other invading genomic material. From the standpoint of physics and biology, the coevolution of bacteria and phages yields fascinating open questions. 

ics Colloquium
Friday, November 2, 2018
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, October 26, 2018
3:30 PM
Physics Building, Room 204
Susan Coppersmith [Host: Despina Louca]
University of Wisconsin - Madison
""Building a Quantum Computer Using Silicon Quantum Dots""
ABSTRACT:

The steady increase in computational power of information processors over the past half-century has led to smart phones and the internet, changing commerce and our social lives.  Up to now, the primary way that computational power has increased is that the electronic components have been made smaller and smaller, but within the next decade feature sizes are expected to reach the fundamental limits imposed by the size of atoms.  However, it is possible that further huge increases in computational power could be achieved by building quantum computers, which exploit in new ways of the laws of quantum mechanics that govern the physical world.  This talk will discuss the challenges involved in building a large-scale quantum computer as well as progress that we have made in developing a quantum computer using silicon quantum dots.  Prospects for further development will also be discussed.

ics Colloquium
Friday, October 19, 2018
3:30 PM
Physics Building, Room 204

"Available"
ics Colloquium
Friday, October 12, 2018
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, October 5, 2018
3:30 PM
Physics Building, Room 204
Dragana Popovic [Host: Despina Louca]
Florida State University
"Unveiling the Normal State of Cuprate High-Temperature Superconductors: Hidden Order of Cooper Pairs"
ABSTRACT:

Many unusual properties of strongly correlated materials have been attributed to the proximity of quantum phase transitions (QPTs), where different types of orders compete and coexist, and may even give rise to novel phases.  In two-dimensional (2D) systems, the nature of the magnetic-field-tuned QPT from a superconducting to a normal state has been widely studied, but it remains an open question.  Underdoped copper-oxide high-temperature superconductors are effectively 2D materials and thus present a promising new platform for exploring this long-standing problem.  Although in cuprates the normal state is commonly probed by applying a perpendicular magnetic field (H) to suppress superconductivity, the identification and understanding of the H-induced normal state has been a challenge because of the complex interplay of disorder, temperature and quantum fluctuations, and the near-universal existence of charge-density-wave correlations. 

 

This talk will describe recent experimental advances in identifying and characterizing a full sequence of ground states as a function of H in underdoped cuprates.  In both the absence and the presence of charge order, the results demonstrate the key role of disorder in the H-tuned suppression of 2D superconductivity, giving rise to an intermediate regime with large quantum phase fluctuations, in contrast to the conventional scenario.  Most strikingly, the interplay of the “striped” charge order with high-temperature superconductivity leads to the emergence of an unanticipated, insulatinglike ground state with strong superconducting phase fluctuations, suggesting an unprecedented freezing (i.e. “the hidden order”) of Cooper pairs.  Possible scenarios will be discussed, including the implications of the results for understanding the physics of the cuprate pseudogap regime, as well as other 2D superconductors.

ics Colloquium
Thursday, October 4, 2018
3:30 PM
Physics Building, Room 204
Utpal Chatterjee [Host: Bob Jones]
University of Virginia - Department of Physics
"Charge density wave phase transitions in transition metal dichalcogenides"
ABSTRACT:

Layered transition-metal dichalcogenides (TMDs) are well known for their rich phase diagrams, which
encompass diverse quantum states including metals, semiconductors, Mott insulators, superconductors, and
charge density waves (CDWs). For instance, 2H-NbSe2 and 2H-TaS2 are canonical incommensurate CDW
systems, while 1T-TiSe2 harbors a commensurate CDW order. There is a coexistence/competition of CDW
and superconductivity in 2H-NbSe2 and 2H-TaS2, though this is not the case for pristine 1T-TiSe2. A subtle
interplay of CDW and superconducting orders, however, appears in each of these materials via chemical
intercalation or under pressure. Such a competition between or coexistence of proximate broken-symmetry
phases resembles many aspects of the phase diagram of cuprate high temperature superconductors
(HTSCs)—particularly, in the underdoped regime where the enigmatic pseudogap phase exists. The origin
of the CDW order in these compounds is an intriguing puzzle despite decades of research. We will present
our experimental data, which combine Angle Resolved Photoemission Spectroscopy, Scanning Tunneling
Spectroscopy, scattering and transport measurements, to provide new insights into the relative importance
of lattice and Coulomb effects in the CDW transitions of these compounds. These studies will also highlight
the distinctive impacts of disorder and doping in commensurate and incommensurate CDW systems.
Finally, comparing spectroscopic features of the CDW state of the TMDs with those of the normal state
underdoped HTSCs, we will discuss whether a CDW order can possibly be the origin of the pseudogap
phase in the cuprates.

ics Colloquium
Friday, September 28, 2018
3:30 PM
Physics Building, Room 204
Roxanne Springer [Host: Simonetta Liuti]
Duke University
"Feynmanʼs Footprints: Quantum Field Theory in Nuclear and Particle Physics"
ABSTRACT:

2018 is the 100th Anniversary of the birth of Richard Feynman.
His discoveries and new formalisms, and the way he thought about
solving problems, transformed the way we think
about physics. I will talk about examples of how these impacted present results
in nuclear and particle physics.

I will also expand upon what might be called Feynmanʼs Scientific Method,
and how by following that method we can become better scientists ourselves
and nurture the next generation of scientists.

ics Colloquium
Monday, September 24, 2018
3:30 PM
Physics Building, Room 203
Diana Vaman [Host: Bob Jones]
University of Virginia - Physics
"Emergent Gravity"
 
 Slideshow (PDF)
ABSTRACT:

Is gravity a fundamental force? I will discuss a few scenarios in which gravity emerges from the dynamics of some underlying field theory. In holography (or AdS/CFT correspondence), Einstein's equations for the bulk gravity dual are linked to entanglement in the boundary field theory. In another example, the graviton emerges as a composite spin two massless particle in a scalar field theory.

SLIDESHOW:
ics Colloquium
Friday, September 21, 2018
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, September 14, 2018
3:30 PM
Physics Building, Room 204

"Available"
ics Colloquium
Friday, September 7, 2018
3:30 PM
Physics Building, Room 204
Evelyn Thomson [Host: Chris Neu]
University of Pennsylvania
"Searching for Supersymmetry with the ATLAS experiment"
ABSTRACT:

The ATLAS experiment is searching new territory for evidence of new particles produced in proton collisions at the highest energies.  Questioning assumptions is important in these searches. I will compare selected results from searches for supersymmetry with and without the assumption of R-Parity, a quantum number derived from the spin and type of particle.  I will also present some of the detector-related challenges associated with measuring charged particle momenta, including the planned upgrade of the detector to cope with up to 200 proton collisions every 25 nanoseconds.

ics Colloquium
Friday, August 31, 2018
3:30 PM
Physics Building, Room 204
Please See Condensed Matter Seminar Schedule
ics Colloquium
Friday, April 27, 2018
3:30 PM
Physics Building, Room 204
Andre Luiz De Gouvea [Host: P. Q. Hung]
Northwestern University
"The Brave nu World"
 
 Slideshow (PDF)
ABSTRACT:

I will review the current theoretical and phenomenological status of neutrino physics. In more detail, I will discuss our current understanding of neutrino properties, open questions, some new physics ideas behind nonzero neutrino masses, and the challenges of piecing together the neutrino mass puzzle. I will also comment on the new physics reach of the current and the next generation of neutrino oscillation experiments. 

SLIDESHOW:
ics Colloquium
Thursday, April 26, 2018
3:30 PM
Physics Building, Room 204
Kerry Vahala [Host: OSA/SPIE Student Chapter]
Caltech
"High-Q Optical Micro-cavities: Towards Integrated Optical Time Standards and Frequency Synthesizers"
ABSTRACT:

Communication systems leverage the respective strengths of optics and electronics to convey high-bandwidth signals over great distances.  These systems were enabled by a revolution in low-optical-loss dielectric fiber, complex integrated circuits as well as devices that link together the optical and electrical worlds.  Today, another revolution is leveraging the advantages of optics and electronics in new ways.  At its center is the laser frequency comb which provides a coherent link between these two worlds. Significantly, because the link is also bidirectional, performance attributes previously unique to electronics and optics can be shared. The end result has been transformative for time keeping, frequency metrology, precision spectroscopy, microwave-generation, ranging and other technologies. Even more recently, low-optical-loss dielectrics, now in the form of high-Q optical resonators, are enabling the miniaturization of frequency combs. These new `microcombs’ can be integrated with electronics and other optical components to potentially create systems on-a-chip.  I will briefly overview the history and elements of frequency combs as well as the physics of the new microcombs. Application of the microcombs for spectroscopy and LIDAR will be discussed.  Finally, efforts underway to develop integrated optical clocks and integrated optical frequency synthesizers using the microcomb element are described.

ics Colloquium
Friday, April 20, 2018
3:30 PM
Physics Building, Room 204
Prof. Jean-Marc Lévy-Leblond (Emeritus) [Host: Olivier Pfister]
"Teaching physics as it is done: A plea for qualitative methods "
ABSTRACT:

It is customary for young physicists, when entering their professional career, to be astonished by the huge difference between physics as it is done and physics as it is taught. The purpose is to show that teaching of physics as it is done is indeed possible and should be encouraged, despite the undeniable existence of didactical, epistemological and institutional obstacles. 

 

ics Colloquium
Friday, April 13, 2018
3:30 PM
Physics Building, Room 204
James Wyant [Host: OSA/SPIE Student Chapter]
University of Arizona
"Using Dynamic Interferometry to Measure Optics of Next Generation Telescopes"
ABSTRACT:

There are currently several large telescope projects. One new telescope is the James Webb Space Telescope (JWST) which is planned to be launched into space on an Ariane 5 rocket from French Guiana in Spring 2019. It is expected that JWST will be the premier observatory of the next decade, serving thousands of astronomers worldwide. It will study every phase in the history of our Universe, ranging from the first luminous glows after the Big Bang, to the formation of solar systems capable of supporting life on planets like Earth, to the evolution of our own Solar System. The primary mirror will consist of 18 mirror segments made of beryllium coated with gold to give a total aperture diameter of 6.5 m. It is critical that the 18 mirror segments are properly phased so they perform as a single 6.5 m diameter mirror. JWST's backplane is the large structure that holds and supports the big hexagonal mirrors of the telescope. The backplane has an important job as it must carry not only the 6.5 m diameter primary mirror plus other telescope optics, but also the entire module of scientific instruments. The mechanical stability and thermal characteristics of the graphite composite backplane are extremely important for optimum performance of the telescope. JWST has many challenging optical testing requirements including a) Primary mirror figure testing, b) Back structure measurement, c) Segment phasing, d) Thermal and mechanical strain, and e) Vibrational dynamics.

 

Another telescope currently being constructed is the Giant Magellan Telescope (GMT), a large ground-based telescope consisting of seven 8.5 m diameter mirrors that will be built on a peak in the Andes Mountains near several existing telescope facilities at Las Campanas, Chile at an altitude of over 2,550 meters. The seven 8.4 m diameter mirror segments will be phased to give a telescope having the resolving power of a telescope 24.5 meters in diameter. GMT is expected to be operational for many decades, enabling breakthrough science ranging from studies of the first stars and galaxies in the universe to the exploration of extrasolar alien worlds. The GMT is poised to answer some of humanity’s biggest questions about the nature of exoplanets and whether we are alone in the universe, about the beginning of the universe to understand the formation and evolution of the galaxies, about the origin of the chemical elements, and how black holes grow. Like the JWST, the GMT has many challenging testing requirements.

During this talk we will describe the JWST and the GMT and the dynamic interferometry techniques that have been developed to measure high quality large telescope optics and the surface vibration and stability characteristics of the supporting structure required for high-quality performance large telescopes.

ics Joint Colloquium with Physics and Astronomy/NRAO


Friday, April 6, 2018
3:30 PM
Physics Building, Room 203
Nicolas Yunes [Host: Kent Yagi]
Montana State University
"What are Gravitational Waves telling us about Theoretical Physics "
ABSTRACT:

The recent gravitational wave observations of the collision of black holes and of neutron stars have allowed us to pierce into the extreme gravity regime, where gravity is simultaneously unfathomably large and wildly dynamical.  These waves encode a trove of information about physics that is prime for the taking, including potential revelations about the validity of Einstein's theory of General Relativity and about nuclear physics in the extreme gravity regime. In this talk, I will describe some of the inferences we can make on both theoretical and nuclear physics from current and future gravitational wave observations. 

ics Colloquium
Friday, March 30, 2018
3:30 PM
Physics Building, Room 204
Adam Kaminski [Host: Utpal Chatterjee]
Iowa State and Ames Lab.
"Chasing Relativistic Electrons in Topological Quantum Materials"
 
 Slideshow (PDF)
ABSTRACT:

The discovery of Dirac fermions in graphene has inspired a search for Dirac and Weyl semimetals in three dimensions thereby making it possible to realize exotic phases of matter first proposed in particle physics. Such materials are characterized by the presence of nontrivial quantum electronic states, where the electron’s spin is coupled with its momentum and Fermi surfaces are no longer closed contours in the momentum space, but instead consist of disconnected arcs. This opens up the possibility for developing new devices in which information is stored and processed using spin rather than charge. Such platforms may significantly enhance the speed and energy efficiency of information storage and processing. In this talk we will discuss the electronic properties of several of newly discovered tellurium based topological quantum materials. In WTe2 we have observed a topological transition involving a change of the Fermi surface topology (known as a Lifshitz transition) driven by temperature. The strong temperature-dependence of the chemical potential that is at the heart of this phenomenon is also important for understanding the thermoelectric properties of such semimetals. In a close cousin, MoTe2, by using high-resolution laser based Angle Resolved Photoemission Spectroscopy (ARPES) we identify Weyl points and Fermi surface arcs, showing a new type of topological Weyl semimetal with electron and hole pockets that touch at a Weyl point. I will also present evidence for a new topological state in PtSn4, that manifests itself by presence of set of extended arcs rather than Dirac points, and so far is not yet understood theoretically. These results open up new directions for research aimed at enhancing topological responsiveness of new quantum materials.

SLIDESHOW:
ics Colloquium
Friday, March 23, 2018
3:30 PM
Physics Building, Room 204
William Bialek [Host: Marija Vucelja]
Princeton University
"Statistical mechanics for networks of real neurons"
 
 Slideshow (PDF)
ABSTRACT:

Thoughts, memories, percepts, and actions all result from the interactions among large numbers of neurons.  Physicists have long hoped that these emergent behaviors could be described using ideas from statistical mechanics.  Recent experimental developments have made it possible to monitor, simultaneously, the electrical activity in hundreds or even thousands of cells.  I will describe surprisingly simple statistical physics models that provide a detailed, quantitative account of these data, and then turn to renormalization group ideas that allow us to search explicitly for some underlying simplicity.  There are signs that real networks are described by non-trivial fixed points, setting the stage for more ambitious theorizing.

http://www.princeton.edu/~wbialek/wbialek.html

SLIDESHOW:
ics Hoxton Lecture


Thursday, March 22, 2018
7:00 PM
Chemistry , Room 402
William Bialek [Host: Marija Vucelja]
Princeton University
"The Physics of Life"
 
 Slideshow (PDF)
ABSTRACT:

In the four hundred years since Galileo, the physics community has constructed a remarkably successful mathematical description of the world around us.  From deep inside the atomic nucleus to the structure of the universe on the largest scales, from the flow air over the wing of an airplane to the flow of electrons in a computer chip, we can predict in detail what we see, and what will happen when we look in places we have never looked before.  What are the limits to this predictive power?  In particular, can we imagine a theoretical physicist’s approach to the complex and diverse phenomena of the living world?  Is there something fundamentally unpredictable about life, or are we missing some deep theoretical principles that could bring the living world under the predictive umbrella of physics?  Exploring this question gives us an opportunity to reflect on what we expect from our scientific theories, and on many beautiful phenomena.  I hope to leave you with a deeper appreciation for the precision of life’s basic mechanisms, and with optimism about the prospects for better theories. 

VIDEO:
ics Joint Colloquium with Physics and Astronomy/NRAO


Friday, March 16, 2018
3:30 PM
Physics Building, Room 203
Imre Bartos [Host: Kent Yagi]
University of Florida
"Multi-messenger Astrophysics in Light of LIGO’s Recent Discoveries"
ABSTRACT:

The recent discoveries of gravitational waves unveiled numerous opportunities in astrophysics, as well as in the study of the cosmos and the laws of physics.  In particular, the multi-messenger detection of binary neutron-star merger GW170817 through gravitational waves and across the electromagnetic spectrum already delivered several important results. I will outline what we learned from GW170817 so far (its remnant is still observable!), along with the opportunities and challenges of near-future multi-messenger observations that will broaden our horizon with gravitational waves in the next few years.  We can expect the proliferation of detected binary neutron star and binary black hole mergers, along with the large-scale efforts to rapidly identify the electromagnetic and neutrino counterparts of these events.  Frequent multi-messenger observations will enable the study of exceptional events, source populations, and sufficient statistics to probe new physics and cosmology.

   

ics Special Seminar with Q&A Session


Wednesday, March 14, 2018
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, March 2, 2018
3:30 PM
Physics Building, Room 204
Peter Schauss [Host: Bob Jones]
Princeton University
"Quantum gas microscopy of many-body dynamics in Fermi-Hubbard and Ising systems"
ABSTRACT:

The ability to probe and manipulate cold atoms in optical lattices at the atomic level using quantum gas microscopes enables quantitative studies of quantum many-body dynamics. While there are many well-developed theoretical tools to study many-body quantum systems in equilibrium, gaining insight into dynamics is challenging with available techniques. Approximate methods need to be benchmarked, creating an urgent need for measurements in experimental model  systems. In this talk, I will discuss two such measurements. First, I will present a study that probes the relaxation of density modulations in the doped Fermi-Hubbard model. This leads to a hydrodynamic description that allows us to determine the conductivity. We observe bad metallic behavior that we compare to predictions from finite-temperature Lanczos calculations and dynamical mean field theory. Second, I introduce a new platform to study the 2D quantum Ising model. Via optical coupling of atoms in an optical lattice to a low-lying Rydberg state, we observe quench dynamics in the resulting Ising model and prepare states with antiferromagnetic correlations.

ics Special Colloquium


Thursday, March 1, 2018
3:30 PM
Physics Building, Room 204
Dmytro Pesin [Host: Israel Klich ]
University of Utah
"Optical and transport properties of geometric metals"
ABSTRACT:

The effects of band geometry on measurable properties of electronic systems have been one of the central subjects in the recent history of condensed matter physics. In this talk, I will describe how non-trivial topology and, more generally, geometry of gapless electronic phases manifest in their optical and transport characteristics.  The main focus of the talk will be on optical anomalous Hall effect and optical activity of Weyl metals, kinetic magnetoelectric effect in noncentrosymmetric conductors, as well as disorder physics in these materials. 

ics Special Colloquium


Friday, February 23, 2018
3:30 PM
Physics Building, Room 204
Brian DeSalvo [Host: Bob Jones]
University of Chicago
"Quantum Mixology: Creating Novel Interacting Bose-Fermi Mixtures with Cs and Li"
ABSTRACT:

A gas of atoms cooled to sufficiently low temperature will form either a Bose-Einstein condensate (BEC) or a degenerate Fermi gas (DFG) depending on the quantum statistics of the constituent particles. But what happens when you combine a BEC and a DFG in an optical trap and add a healthy dose of interspecies interactions? Mean-field theory predicts three possible outcomes: a miscible mixture for weak interactions, complete demixing for strong repulsive interactions, or a spectacular collapse due to the loss of mechanical stability for strong attractive interactions. In this talk, I will discuss our efforts to answer this question experimentally in the specific case where the bosons are much heavier than the fermions. To this end, we have created the first quantum degenerate mixture of bosonic 133Cs and fermionic 6Li and used an interspecies Feshbach resonance to tune the interactions between the bosons and fermions. For attractive interspecies interactions, we find two surprising results. First,  we show that a degenerate Fermi gas of Li can be trapped by a Cs BEC, even in the absence of external potentials. Second, for strong attractive interactions where collapse is predicted, we observe no such instability. I will discuss the mechanisms at play to explain these results and comment on current and future studies delving deeper into these unexpected regimes.

 

 

ics Special Colloquium


Monday, February 19, 2018
3:30 PM
Physics Building, Room 204
Wade Hsu [Host: Bob Jones]
Yale University
"New Frontiers of Electromagnetic Phenomena at the Nanoscale"
ABSTRACT:

Optics and photonics today enjoy unprecedented freedom. The ability to synthesize arbitrary light fields (through wavefront shaping) and the ability to design structures at the subwavelength scale (through nanofabrication) enable us to realize phenomena that could only be imagined in the past. In this talk, I will present several experiments and related theory that demonstrate exciting new phenomena which were previously inaccessible. A) Conventional textbook wisdom is that waves cannot be perfectly confined within the continuum spectrum of an open systems. Exceptions called “bound states in the continuum” were hypothesized by von Neumann and Wigner [1] but not realized. I will describe the first realization of such unusual states [2] and their manifestation as polarization vortices protected by topologically conserved “charges” [3]. B) Our ability to control radiation also enables the realization of non-Hermitian phenomena with no counterpart in closed systems. I will show how non-Hermiticity generates unique topologies in photonic band structures and lead to enhanced lightmatter interactions [4,5]. C) Strong disorder in naturally occurring light-scattering media allows us to study mesoscopic physics in a new arena. I will describe the control of optical transport via wavefront shaping, and how the long-range correlations between multiply scattered photons enable us to simultaneously control orders of magnitudes more degrees of freedom than previously thought possible [6,7].

 

[1] C. W. Hsu*, B. Zhen* et al., Nature Reviews Materials 1, 16048 (2016).

[2] C. W. Hsu*, B. Zhen* et al., Nature 499, 188 (2013).

[3] B. Zhen*, C. W. Hsu* et al., Phys. Rev. Lett. 113, 257401 (2014).

[4] B. Zhen*, C. W. Hsu* et al., Nature 525, 354 (2015).

[5] H. Zhou et al., Science, eaap9859 (2018).

[6] C. W. Hsu et al., Phys. Rev. Lett. 115, 223901 (2015).

[7] C. W. Hsu et al., Nature Physics 13, 497 (2017).

ics Special Colloquium


Friday, February 16, 2018
3:30 PM
Physics Building, Room 204
Haitan Xu [Host: Bob Jones]
Yale University
"Topological and nonreciprocal dynamics in an optomechanical system"
ABSTRACT:

Non-Hermitian systems exhibit rich physical phenomena that open the door to qualitatively new forms of control. In this talk, I will introduce our recent work on topological and nonreciprocal dynamics in a non-Hermitian optomechanical system. Specifically, we realized topological energy transfer between nearly degenerate modes by adiabatically encircling an exceptional point (a singularity of the complex spectrum). We also demonstrated that this energy transfer is non-reciprocal: a given topological operation can only transfer energy in one direction. We have extended the topological and nonreciprocal dynamics to highly non-degenerate modes by exploiting a generic form of nonlinearity, which should allow these effects to be exploited in a very wide range of physical systems. In addition, we realized nonreciprocal dynamics by optomechanical interference.

 

ics Colloquium
Monday, February 12, 2018
3:30 PM
Physics Building, Room 204
Gia-Wei Chern
UVA-Department of Physics
"Quantum Molecular Dynamics of Strongly Correlated Electron Materials"
ABSTRACT:

I will present a new formulation of quantum molecular dynamics for strongly correlated materials. Our novel scheme enables the study of the dynamical behavior of atoms and molecules with strong electron correlations. In particular, our scheme is based on the efficient Gutzwiller method that goes beyond the conventional mean-field treatment of the intra-atomic electron repulsion and captures crucial correlation effects such as band narrowing and electron localization. We use Gutzwiller quantum molecular dynamics to investigate the Mott metal-insulator transition in the liquid phase of a single-band metal and uncover intriguing structural and transport properties of the atoms. I will also discuss future plans for large-scale dynamical simulations of strongly correlated systems.

ics Joint Colloquium with Physics and Astronomy/NRAO


Friday, February 9, 2018
3:30 PM
Physics Building, Room 203
Alexander Ji [Host: Xiaochao Zheng]
Carnegie Observatories
"A Rare and Prolific r-process Event Preserved in an Ultra-Faint Dwarf Galaxy"
ABSTRACT:

The heaviest elements in the periodic table are synthesized through the rapid neutron-capture process (r-process), but the astrophysical site producing these elements has been a long-standing conundrum. Ultra-faint dwarf galaxies contain a simple fossil record of early chemical enrichment that provide an ideal laboratory to investigate the origin of r-process elements. Previous measurements found very low levels of neutron-capture elements in ultra-faint dwarfs, preferring supernovae as the r-process site. I present high-resolution chemical abundances of nine stars in the recently discovered ultra-faint dwarf Reticulum II, which display extremely enhanced r-process abundances 2-3 orders of magnitude higher than the other ultra-faint dwarfs. Stars with such extreme r-process enhancements are only rarely found in the Milky Way halo. The r-process abundances imply that the neutron-capture material in Reticulum II was synthesized in a single prolific event that is incompatible with r-process yields from ordinary core-collapse supernovae but consistent with a neutron star merger. Together with the recent gravitational wave observations of a neutron star merger and its electromagnetic afterglow, it is now clear that neutron star mergers dominate cosmic production of r-process elements.

ics Special Colloquium


Thursday, February 8, 2018
3:30 PM
Physics Building, Room 204
Thomas Scaffidi [Host: Israel Klich]
University of California, Berkeley
"Electron hydrodynamics in solid-state physics"
ABSTRACT:

Wolfgang Pauli called solid-state physics "the physics of dirt effects", and this name might appear well-deserved at first sight since transport properties are more often than not set by extrinsic properties, like impurities. In this talk, I will present solid-state systems in which electrons behave hydrodynamically, and for which transport properties are instead set by intrinsic properties, like the viscosity. This new regime of transport opens the way for a “viscous electronics”, and provides a new angle to study how quantum mechanics can constrain and/or enrich hydrodynamics.

ics Special Colloquium


Wednesday, February 7, 2018
3:30 PM
Physics Building, Room 204
Norbert Linke [Host: Bob Jones]
Joint Quantum Institute, University of Maryland, and NIST
"A programmable quantum computer based on trapped ions"
ABSTRACT:

Quantum computers can solve certain problems more efficiently than any classical computer. Trapped ions are a promising candidate for realizing such a system. We present a modular quantum computing architecture comprised of a chain of 171Yb+ ions with individual Raman beam addressing and individual readout [1]. We use the transverse modes of motion in the chain to produce entangling gates between any qubit pair. This creates a fully connected system which can be configured to run any sequence of single- and two-qubit gates, making it in effect an arbitrarily programmable quantum computer that does not suffer any swap-gate overhead [2].
Recent results from different quantum algorithms on five and seven ions will be presented [3,4], including a quantum error detection protocol that fault-tolerantly encodes a logical qubit [5]. I will also discuss current work and ideas to scale up this architecture.

[1] S. Debnath et al., Nature 563:63 (2016).
[2] NML et al., PNAS 114 13:3305 (2017).
[3] C. Figgatt et al., Nat. Communs. 8, 1918 (2017).
[4] NML et al., arXiv:1712.08581 (2017)
[5] NML et al., Sci. Adv. 3, 10 (2017).


 

ics Special Colloquium


Monday, February 5, 2018
3:30 PM
Physics Building, Room 204
Peter Maurer [Host: Bob Jones]
Stanford University
"Quantum sensing in a new single-molecule regime"
ABSTRACT:

Quantum optics has had a profound impact on precision measurements, and recently enabled probing various physical quantities, such as magnetic fields and temperature, with nanoscale spatial resolution. Such advancements in ‘quantum sensing’ have brought the elusive dream of performing nuclear magnetic resonance spectroscopy (NMR) on individual biomolecules closer to reality. In my talk, I will discuss the development and application of novel quantum metrological technologies to study biological systems at a single-molecule level. I will start with a general introduction to quantum sensing, with a focus on the measurement of magnetic fields at a nanoscale. I will then show how we utilize such sensing techniques to control the temperature profile in living systems with subcellular resolution. Finally, I will provide an outlook on how quantum sensing and single-molecule biophysics can be utilized to perform NMR spectroscopy with unprecedented sensitivity, possibly down to the level of individual biomolecules.

 

ics Special Colloquium


Friday, February 2, 2018
3:30 PM
Physics Building, Room 204
Yuxuan Wang [Host: Israel Klich ]
UIUC
"Topological Superconductivity From Electronic Interactions"
ABSTRACT:

Topological superconductors exhibit exotic Majorana modes at the boundaries and vortices, and can provide important applications in quantum computing. In addition to usual path of “engineering” topological superconductivity with heterostructure of conventional superconductors, we show that intrinsic topological superconductivity can also be naturally realized through electron-electron interactions. Specifically, we analyze the topological superconducting state that emerges near the onset of an inversion-breaking electronic order. Other than topological superconductivity, we show that the system has an enhanced U(1)xU(1) symmetry as well as a rich phase diagram. We address the relevance of our results with recent experiments in Cd2Ce2O7 and half-Heusler superconductors. We argue that important progress can be made at the intersection of topological superconductivity and unconventional superconductivity.

ics Special Colloquium


Friday, January 26, 2018
3:30 PM
Physics Building, Room 204
Sho Yaida [Host: Israel Klich ]
Duke University
"Imprints of complex landscapes on glassy materials"
ABSTRACT:

Amorphous solids are omnipresent in everyday life, from window glasses to plastics to piles of sand. Yet our understanding of their properties lags far behind that of their crystalline counterparts. Recent advances are rapidly changing the way in which we understand these materials. This talk overviews two such advances: (i) the algorithmic developments that link dramatic slowdown of glass-forming liquids to growing amorphous order, and (ii) the discovery of the critical replica-symmetry-breaking transition within solid glasses. Taken together, these results reinforce the overriding role of rugged free-energy landscapes in controlling glassiness.

ics Special Colloquium


Tuesday, January 23, 2018
3:30 PM
Physics Building, Room 204
Jennifer Cano [Host: Israel Klich ]
Princeton University
"Topological Quantum Chemistry"
ABSTRACT:

The past decade's apparent success in predicting and experimentally discovering distinct classes of topological insulators (TIs) and semimetals masks a fundamental shortcoming: out of 200,000 stoichiometric compounds extant in material databases, only several hundred of them are topologically nontrivial. Are TIs that esoteric, or does this reflect a fundamental problem with the current piecemeal approach to finding them? To address this, we propose a new and complete electronic band theory that highlights the link between topology and local chemical bonding, and combines this with the conventional band theory of electrons. We classify the possible band structures for all 230 crystal symmetry groups that arise from local atomic orbitals, and show which are topologically nontrivial. We show how our topological band theory sheds new light on known TIs, and demonstrate the power of our method to predict new TIs.

ics Colloquium
Friday, January 19, 2018
3:30 PM
Physics Building, Room 204
David Meyer [Host: Olivier Pfister]
University of California at San Diego
"Constraints on multiparticle entanglement"
ABSTRACT:

States of a multiparticle quantum system are useful for quantum information processing when they are entangled, i.e., not product states relative to the tensor product decomposition of the Hilbert space corresponding to the particles.  Arbitrary entanglements between parts of a quantum system are not possible, however; they must satisfy certain “monogamy” constraints which limit how much multiple different subsystems can be entangled with one another.  The standard monogamy constraints can be generalized in several ways:  in this talk we’ll tighten some, generalize others to higher dimensional tensor factors, and derive inequalities satisfied by symmetric sets of entanglement measures.  Along the way we’ll contrast the quantum results with corresponding statements about classical random variables. 

https://math.ucsd.edu/people/profiles/david-meyer/

ics Colloquium
Friday, December 1, 2017
3:30 PM
Physics Building, Room 204
Xiaoliang Qi [Host: Israel Klich ]
Stanford University
"Entanglement, chaos and order"
 
 Slideshow (PDF)
ABSTRACT:

In classical mechanics, chaos refers to the phenomenon that an arbitrarily small perturbation leads to a dramatic change at a later time. The analogous phenomenon in quantum mechanics---quantum chaos is generic in many-body systems. Although chaos makes it difficult to solve the many-body problem exactly, it actually provides new knowledge about dynamics of the system, such as thermalization. In understanding quantum chaos and thermalization, the concept of quantum entanglement plays an essential role. In this talk, I will discuss the connection between several related phenomena, including the dynamics of quantum entanglement, thermalization of isolated systems, and measure of quantum chaos. As a concrete model to study quantum chaos, I will discuss the Sachdev-Ye-Kitaev (SYK) model and its generalizations. This model provides an example of strongly correlated systems in which new kinds of "order" emerges from chaos. Entanglement dynamics in this model suggests an interesting interplay between thermalization and many-body localization.

 

References: arXiv:1511.04021

arXiv:1609.07832 

arXiv:1708.00871

 

SLIDESHOW:
ics Colloquium
Friday, November 17, 2017
3:30 PM
Physics Building, Room 204
Patrick Charbonneau [Host: Marija Vucelja]
Duke University
"Recent Advances on the Glass Problem"
ABSTRACT:

Recent theoretical advances in the mean-field theory of glasses predict the existence, deep in the glass phase, of a novel phase transition, a so-called Gardner transition. This transition signals the emergence of a complex free energy landscape composed of a marginally stable hierarchy of sub-basins. It is also thought to be the onset of the anomalous thermal and transport properties of amorphous systems, and to ultimately lead to the unusual critical behavior at jamming. In this talk, I will present an overview of our recent theoretical and numerical advances in capturing and characterizing this novel materials feature.

ics Colloquium
Friday, November 10, 2017
3:30 PM
Physics Building, Room 204
Vladimir Dobrosavljevic [Host: Gia-Wei Chern]
Florida State University
"Bad Metal Behavior and Mott Quantum Criticality"
ABSTRACT:

According to early ideas of Mott and Anderson, the interaction-­driven metal-­insulator transition “the Mott transition“ remains a sharp T=0 phase transition even in absence of any spin or charge ordering.  Should this phase transition be regarded as a quantum critical point?  To address this question, here we examine the phase diagram and transport properties of the maximally frustrated half-­filled Hubbard model, in the framework of dynamical mean-­field theory (DMFT).  We identify a quantum Widom line (QWL) which defines the center of the corresponding quantum critical region associated with Mott metale insulator transition for this model.  The evolution of resistivity with temperature is then evaluated along trajectories following (parallel to) the QWL, displaying remarkable scaling behavior characteristic of quantum criticality.  Precisely this kind of behavior was found in very recent experiments on organic Mott systems [1,2].  In the case of the doping-driven Mott transition, we show that the mysterious Bad Metal behavior (T-linear resistivity around the Mott-Ioffee- Regel limit) coincides with the Quantum Critical region of the Mott transition.

 

[1] Quantum criticality of Mott transition in organic materials, Tetsuya Furukawa, Kazuya Miyagawa, Hiromi Taniguchi, Reizo Kato & Kazushi Kanoda, Nature Physics, 9 Feb.  2015; doi:10.1038/nphys3235.

[2] See also:

http://condensedconcepts.blogspot.com/2015/03/quantum-criticality-near-mott.html

ics Colloquium
Friday, November 3, 2017
3:30 PM
Physics Building, Room 204
Ted Hodapp [Host: Olivier Pfister]
APS Bridge Program
"APS Bridge Program: Changing the Face of Physics Graduate Education"
ABSTRACT:

In nearly every science, math, and engineering field there is a significant falloff in participation by underrepresented minority (URM) students who fail to make the transition between undergraduate and graduate studies.  The American Physical Society (APS) has realized that a professional society can erase this gap by acting as a national recruiter of URM physics students and connecting these individuals with graduate programs that are eager to a) attract motivated students to their program, b) increase domestic student participation, and c) improve the diversity of their program.  Now in its fifth year the APS has placed enough students into graduate programs nationwide to eliminate this achievement gap.  The program has low costs, is popular among graduate programs, and has inspired other departments to adopt practices that improve graduate admissions and student retention. This presentation will review project activities, present data that demonstrate effectiveness, and discuss future actions.

This material is based upon work supported in part by the National Science Foundation under Grant No. (NSF-1143070).

ics Colloquium
Friday, October 27, 2017
3:30 PM
Physics Building, Room 204
Avi Pe'er [Host: OSA/SPIE Student Chapter]
Bar Ilan University
"Lifting the Bandwidth Limit of Optical Homodyne Measurement - A Key for Broadband Quantum Information"
ABSTRACT:

Homodyne measurement is a corner-stone of quantum optics. It measures the fundamental variables of quantum electrodynamics - the quadratures of light, which represent the cosine-wave and sine-wave components of an optical field. The quadratures constitute the quantum optical analog of position and momentum in mechanics and obey quantum uncertainty, indicating the inherent inability to measure both simultaneously. The homodyne process, which extracts a chosen quadrature amplitude by correlating the optical field against an external quadrature reference (local-oscillator, LO), forms the backbone of coherent detection in physics and engineering, and plays a central role in quantum information processing. Homodyne can reveal non-classical phenomena, such as squeezing of the quadrature uncertainty; It is used in tomography to fully characterize quantum states of light; Homodyne detection can generate non-classical states, provide local measurements for teleportation and serve as a major detector for quantum key distribution (QKD) and quantum computing. Yet, standard homodyne suffers from a severe bandwidth limitation. While the bandwidth of optical states can easily span many THz, standard homodyne detection is inherently limited to the electrically accessible, MHz to GHz range, leaving a dramatic gap between the relevant optical phenomena and the measurement capability. This gap impedes effective utilization of the huge bandwidth resource of optical states and the potential enhancement of the information throughput \emph{by several orders of magnitude} with parallel processing in quantum computation, QKD and other applications of quantum squeezed light. Here we demonstrate a fully parallel optical homodyne measurement across an arbitrary optical bandwidth, effectively lifting the bandwidth limitation completely. Using optical parametric amplification, which amplifies one quadrature while attenuating the other, we measure two-mode quadrature squeezing of 1.7dB below the vacuum level simultaneously across a bandwidth of 55THz using a single LO - the pump. This broadband parametric homodyne measurement opens a wide window for parallel processing of quantum information.

Yaakobv Shaked, Yoad Michael, Rafi Vered, Leon Bello, Michael Rosenbluh and Avi Pe'er, Physics Dept. and BINA center for  Nanotechnology, Bar Ilan University, Ramat Gan 5290002, Israel

ics Colloquium
Friday, October 20, 2017
3:30 PM
Physics Building, Room 204
Simonetta Liuti [Host: Joe Poon]
UVA-Physics
"Tomography of the Atomic Nucleus"
ABSTRACT:

The history of our exploration of subatomic matter has witnessed a major breakthrough with every new probe being introduced. In the 1950’s Hofstadter and collaborators using elastic electron scattering measured for the first time the electromagnetic form factors of nucleons and nuclei and provided the first information on the nuclear spatial charge and magnetization distributions. In the late 1960’s and early 70’s, Friedman, Kendall and Taylor using Deep Inelastic Scattering of electrons off the nucleon, discovered its underlying quark structure displayed in their longitudinal momentum distributions. 

I will discuss probes at the next frontier that will allow us to access dynamically correlated distributions in both momentum and coordinate space -- the Wigner distributions -- at the femtoscale. Deeply Virtual Compton Scattering, namely a high energy lepton scattering off a nucleon target producing a high energy real photon and a small angle recoil proton, is one of such probes. I will explain how a detailed mapping of the quarks and gluons in the nucleon and nucleus in phase space, or a phase-space tomography, besides providing for the first time images of quarks and gluons spatial distributions, is essential for understanding the so far elusive nucleon mass and spin decompositions in terms of its quark and gluon components. 

ics Colloquium
Friday, October 13, 2017
3:30 PM
Physics Building, Room 204
Prem Kumar [Host: Olivier Pfister]
Northwestern University
"All-optical Switching for Photonic Quantum Networks"
 
 Slideshow (PDF)
ABSTRACT:

Quantum internet of the future will require device functionalities that implicitly respect the fundamental facts such as quantum information cannot be copied, and cannot be measured precisely. A quantum repeater, for example,—analog of an optical amplifier that enabled global reach of the ubiquitous Internet connectivity we enjoy today—is yet to be demonstrated, although recent years have seen tremendous progress. Many other device functionalities—switches, routers, format converters, etc.—would also be needed that do not unnecessarily disturb or corrupt the quantum information as it flows from one node of the internet to another. In recent years, my group has engineered an all-optical quantum switch that fulfills many of the requirements for distributing quantum information in a networked environment. In this talk, I will present our motivation, design, construction, characterization, and utilization of such a switch in near-term networked quantum applications.

SLIDESHOW:
ics Colloquium
Friday, October 6, 2017
3:30 PM
Physics Building, Room 204
Kent Paschke [Host: Joe Poon]
UVA-Physics
"Looking for New Physics with the Weak Interaction in Electron Scattering: Recent Results from Qweak and Future Perspectives"
 
 Slideshow (PDF)
ABSTRACT:

The measurement of the violation of parity symmetry in electron scattering has proven to be a powerful technique for exploring nuclear matter and searching for new fundamental forces. In the Standard Model of particle physics, parity violation can only occur through the weak interaction. Precision measurements of this symmetry breaking can test the completeness of this description of the weak force at low energies. I will describe the result of one such measurement - the recently completed Qweak experiment - along with the experimental challenges and triumphs.  Future measurements in the field of parity-violating electron scattering will also be reviewed, including other Standard Model tests and experiments using the weak force to determine the size of a heavy atomic nucleus.

SLIDESHOW:
ics Colloquium
Friday, September 29, 2017
3:30 PM
Physics Building, Room 204
Xiaochao Zheng [Host: Joe Poon]
UVA-Physics
"Peeling the Atomic Onion"
 
 Slideshow (PDF)
ABSTRACT:

The word "atom" (a-tomos) originates from ancient Greek philosophers, who argued that objects can be eventually divided into discrete, small particles, beyond which matter is no longer cuttable.  Our search for the answer to "What the matter is made of" has gone a long way, from the first experimental evidence of atoms in the 1800's, to Rutherford's alpha scattering on gold foils, to modern day's linear accelerators looking into the atomic nucleus. We now understand that matter is made of quarks and leptons, currently named elementary particles (objects of no size) that form the foundation of the Standard Model of Particle Physics. However, if we look back at this journey, one may wish to oppose the view of the ancient Greeks and argue that quarks and leptons cannot be the end of the story, that our quest for peeling the atomic onion may be a timeless journey.

I will discuss the frontier research in electron scattering at the GeV energy level. I will focus on parity violation in electron scattering off the proton and the neutron and the extraction of neutral-weak effective couplings between electrons and quarks, and show how such high precision measurements are now helping us venturing further into the study of subatomic structure. 

SLIDESHOW:
ics Colloquium
Friday, September 22, 2017
3:30 PM
Physics Building, Room 204
Nergis Mavalvala [Host: Cass Sackett]
M.I.T.
"Future directions in gravitational-wave detection"
ABSTRACT:

The Laser Interferometer Gravitational-wave Observatory (LIGO) detected gravitational waves for the first time in 2015. Since then there have been a couple more detections of binary black hole mergers. I will discuss the instruments that made these discoveries, the science so far, and plans for future improvements and upgrades to LIGO. 

VIDEO:
ics Special Colloquium and Hoxton Lecture


Thursday, September 21, 2017
7:00 PM
Chemistry Building, Room 402
Nergis Mavalvala
M.I.T.
"The Warped Universe: the one hundred year quest to discover Einstein’s gravitational waves"
ABSTRACT:

In 2016, scientists announced the first ever detection of gravitational waves from colliding black holes, launching a new era of gravitational wave astrophysics. Gravitational waves were predicted by Einstein a hundred years earlier. I will describe the science, technology, and human story behind these discoveries that provide a window into some of the most violent and warped events in the Universe.

 

ics Colloquium
Friday, September 15, 2017
3:30 PM
Physics Building, Room 204
Cass Sackett [Host: Joe Poon]
UVA-Physics
"Tune-out wavelength spectroscopy: a new technique to characterize atomic structure"
 
 Slideshow (PDF)
ABSTRACT:

When you shine a laser on an atom, the electric field of the light induces a dipole moment, resulting in an energy shift. The dipole can be either parallel or anti-parallel to the field, depending on the frequency of the light. This corresponds to negative or positive energies. At certain frequencies, however, the induced dipole is zero. The corresponding light wavelength is called a tune-out wavelength. The location of the various tune-out wavelengths depend on the electronic wave function in the atom, particularly the dipole matrix elements . So by measuring the tune-out wavelength, the dipole matrix elements can be determined more accurately than by conventional techniques. This is useful because the dipole matrix elements are also used to relate precision atomic experiments like parity violation to fundamental particle properties like the weak mixing angle. We have developed a new technique for measuring  tune-out wavelengths, which should improve our knowledge of many matrix elements by an order of magnitude or more. We hope that this will support new generations of precision atomic measurements.

SLIDESHOW:
ics Colloquium
Friday, September 8, 2017
3:30 PM
Physics Building, Room 204
Tianran Chen [Host: Seunghun Lee]
UVA-Physics
"Origin of Long Lifetime of Band-Edge Charge Carriers in Organic-Inorganic Lead Iodide Perovskites"
ABSTRACT:

Long carrier lifetime is what makes hybrid organic-inorganic perovskites high performance photovoltaic materials. Several microscopic mechanisms behind the unusually long carrier lifetime have been proposed, such as formation of large polarons, Rashba effect, ferroelectric domains, and photon recycling. Here, we show that the screening of band-edge charge carriers by rotation of organic cation molecules can be a major contribution to the prolonged carrier lifetime. Our results reveal that the band-edge carrier lifetime increases when the system enters from a phase with lower rotational entropy to another phase with higher entropy. These results imply that the recombination of the photo-excited electrons and holes is suppressed by the screening, leading to the formation of polarons and thereby extending the lifetime. Thus, searching for organic-inorganic perovskites with high rotational entropy over a wide range of temperature may be a key to achieve superior solar cell performance.

ics Special Physics Forum for Faculty, Students, and Staff


Friday, September 1, 2017
3:30 PM
Physics Building, Room 203
Physics Forum
ics Colloquium
Friday, August 25, 2017
3:30 PM
Physics Building, Room 204

"Available"
ics Colloquium
Friday, April 28, 2017
3:30 PM
Physics Building, Room 204
John Beacom [Host: Craig Group]
Ohio State
"Making Neutrino Astronomy Real"
ABSTRACT:

For over 50 years, people have been discussing the promise of high-energy neutrino astronomy.  For most of that time, wholesale theoretical conjecture was unmatched by even a trifling return of measured experimental facts.  Then in 2013, the IceCube neutrino observatory discovered astrophysical neutrinos with energies up to fifteen orders of magnitude above those of visible light.  What does this mean for understanding astrophysical sources, the properties of neutrinos, and the contents of the Universe?

ics Colloquium
Wednesday, April 26, 2017
3:30 PM
Physics Building, Room 204
Kerry Vahala [Host: OSA/SPIE Student Chapter]
Caltech
ics Annual Physics Day Show


Wednesday, April 26, 2017
7:00 PM
Physics Building, Room 204
Annual Physics Day
ABSTRACT:

The University of Virginia Physics Department Presents the 23rd Annual National Physics Day Show

Observing the Universe with Physics

 


Wednesday, April 26, 2017, 7:00 p.m.
Physics Building, Room 203
382 McCormick Road, Charlottesville, Virginia

A Family-Oriented Event! Free! Open to the Public!
Come see an hour of exciting and intriguing demonstrations!
For more information about this event, call 434-924-3781. Free public parking is available in nearby Scott Stadium lots.

For a map showing the location of the Physics Building, see:
http://www.virginia.edu/webmap/popPages/76-PhysicsBldg_Jesse.html

ics Colloquium
Friday, April 21, 2017
3:30 PM
Physics Building, Room 204
Nora Berrah [Host: Despina Louca]
University of Connecticut
"Probing Molecular Dynamics from Within using FELs"
ABSTRACT:

Short x-ray pulses from free electron lasers (FELs) open a new regime for all scientific research. The first x-ray FEL, the Linac Coherent Light Source (LCLS) at the SLAC National Laboratory on the Stanford campus, provides intense short pulses that allow the investigation of ultrafast non-linear and multi-photon processes, including time-resolved investigations in molecules. We will report on the femtosecond response of molecules to the ultra-intense, ultrafast x-ray radiation from FELs as well as on time-resolved investigation using x-ray pump-x-ray probe techniques.

ics Colloquium
Friday, April 14, 2017
3:30 PM
Physics Building, Room 204
Gregory Falkovich [Host: Marija Vucelja]
Weizmann Institute
"Negative resistance and other wonders of viscous electronics in graphene"
 
 Slideshow (PDF)
ABSTRACT:

Quantum-critical strongly correlated systems feature universal collision-dominated collective transport. Viscous electronics is an emerging field dealing with systems in which strongly interacting electrons flow like a fluid. We identified vorticity as a macroscopic signature of electron viscosity and linked it with a striking macroscopic DC transport behavior: viscous friction can drive electric current against an applied field, resulting in a negative resistance, recently measured experimentally in graphene. I shall also describe current vortices, expulsion of electric field, conductance exceeding the fundamental quantum-ballistic limit and other wonders of viscous electronics. Strongly interacting electron-hole plasma in high-mobility graphene affords a unique link between quantum-critical electron transport and the wealth of fluid mechanics phenomena.

http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys3667.html

https://arxiv.org/abs/1607.00986  

http://arxiv.org/abs/1607.07269

SLIDESHOW:
ics Colloquium
Friday, April 7, 2017
3:30 PM
Physics Building, Room 204
Adolfo Del Campo [Host: Israel Klich ]
University of Massachusetts
"[CANCELED] Engineering Quantum Thermal Machines"
ABSTRACT:

Quantum thermodynamics has emerged as an interdisciplinary research field in quantum science and technology with widespread applications. Yet, the identification of scenarios characterized by quantum supremacy -a performance without match in the classical world- remains challenging. In this talk I shall review recent advances in the engineering and optimization of quantum thermal machines. I will show that nonadiabatic many-particle effects can give rise to quantum supremacy in finite-time thermodynamics [1]. Tailoring such nonadiabatic effects by making use of shortcuts to adiabaticity, quantum heat engines can be operated at maximum efficiency and arbitrarily high output power [2]. A thermodynamic cost of these shortcuts will be elucidated by analyzing the full work distribution function and introducing a novel kind of work-energy uncertainty relation [3]. I shall close by discussing the identification of scenarios with a quantum-enhanced performance in thermal machines run over many cycles [4]. 

Bibliography: 
[1] J. Jaramillo, M. Beau, A. del Campo, New J. Phys. 18, 075019 (2016). 
[2] M. Beau, J. Jaramillo, A. del Campo, Entropy 18, 168 (2016). 
[3] K. Funo, J.-N. Zhang, C. Chatou, K. Kim, M. Ueda and A. del Campo, Phys. Rev. Lett, 118, 100602 (2017).
[4] G. Watanabe, B. P. Venkatesh, P. Talkner and A. del Campo, Phys. Rev. Lett. 118, 050601 (2017).

 

ics Special Colloquium


Friday, March 31, 2017
9:00 AM
The Rotunda, Room Dome Room
George Crabtree [Host: Bellave Shivaram]
Joint Center for Energy Storage Research (JCESR) Argonne National Laboratory and University of Illinois at Chicago
"Storage at the Threshold: Li-ion Batteries and Beyond"
ABSTRACT:

The high energy density and low cost of lithium-ion batteries have created a revolution in personal electronics through laptops, tablets, smart phones and wearables, permanently changing the way we interact with people and information.  We are at the threshold of similar transformations in transportation to electric cars and in the electricity grid to renewable generation, smart grids and distributed energy resources.  Many aspects of these transformations require new levels of energy storage performance and cost that are beyond the reach of Li-ion batteries.  Next generation beyond Li-ion batteries and their potential to meet these performance and cost thresholds will be analyzed.

George Crabtree, Elizabeth Kocs and Lynn Trahey, The energy-storage frontier: Lithium-ion batteries and beyond, MRS Bulletin 40, 1067 (2015)

Bio: George Crabtree is Director of the Joint Center for Energy Storage (JCESR) at Argonne National Laboratory and Professor of Physics, Electrical, and Mechanical Engineering at University of Illinois-Chicago (UIC).  He has wide experience in next-generation battery technology and integrating energy science, technology, policy and societal decision-making. He has led workshops for the Department of Energy on energy science and technology, is a member of the National Academy of Sciences and has testified before the U.S. Congress

 

ics Colloquium
Friday, March 31, 2017
3:30 PM
Physics Building, Room 204
Kirsten Tollefson [Host: Chris Neu]
Michigan State University
"A New Way to Look at the Sky"
ABSTRACT:

The High Altitude Water Cherenkov (HAWC) Gamma-ray Observatory was completed in March 2015 and is now giving us a new view of the sky. HAWC is a continuously operating, wide field-of-view observatory sensitive to 100 GeV – 100 TeV gamma rays and cosmic rays. It is 15 times more sensitive than previous generation extensive air shower gamma-ray instruments. It serves as a “finder” telescope and monitors the same sky as gamma-ray satellites (Fermi), gravity-wave (LIGO) detectors and neutrino observatories (IceCube) allowing for multi-wavelength and multi-messenger observations.  HAWC hopes to answer questions such as "what is dark matter?” and “where do cosmic rays come from?” by observing some of the most violent processes in our Universe. I will present highlights from HAWC’s first year of operation.

ics Colloquium
Friday, March 24, 2017
3:30 PM
Physics Building, Room 204
Ariel Amir [Host: Marija Vucelja]
Harvard University
"Controlling cell size and DNA replication in bacteria - insights from mathematical modeling"
ABSTRACT:

Understanding how cells control and coordinate the various ongoing cellular processes, such as DNA replication, growth and division is an outstanding fundamental problem in biology. Remarkably, bacterial cells may divide faster than their chromosomes replicate, implying that cells maintain multiple rounds of chromosome replication, and that tight control over DNA replication must be in place. I will show how ideas from statistical mechanics and mathematical modeling can serve as alternative "microscopes" into this problem. Our results suggest that both cell size and chromosome replication may be simultaneously regulated by following a simple control mechanism, in which, effectively, a constant volume is added between two DNA replication initiation events. This model elucidates the experimentally observed correlations between various events in the cell cycle, and explains the exponential dependence of cell size on the growth rate, as well as recent experiments in which cell morphology is perturbed.

http://amir.seas.harvard.edu/

ics Special Colloquium


Thursday, March 23, 2017
7:00 PM
The Rotunda, Room Dome Room
Francis Halzen [Host: Craig Group]
UW - Wisconsin
"Ice Fishing for Neutrinos at the South Pole"
 
 Slideshow (PDF)
ABSTRACT:

The IceCube project at the South Pole has melted eighty-six holes over 1.5 miles deep in the Antarctic icecap for use as astronomical observatories. The project recently discovered a flux of neutrinos reaching us from the cosmos, with energies more than a million times those of the neutrinos produced at accelerator laboratories. These neutrinos are astronomical messengers from some of the most violent processes in the universe--giant black holes gobbling up stars in the heart of quasars and gamma-ray bursts, the biggest explosions since the Big Bang.

In a special public lecture, brought to you by the departments of physics, astronomy, and NRAO Francis Halzen, Gregory Breit Professor and Hilldale Professor of Physics at UW-Madison and the principal investigator of IceCube, will tell the story of the IceCube telescope and discuss highlights from recent scientific results.

 

SLIDESHOW:
ics Colloquium
Friday, March 17, 2017
3:30 PM
Physics Building, Room 203
Bill Phillips [Host: Sanjay Khatri - OSA Student Chapter]
NIST
"Manipulating atoms with light: from spectroscopy to atomtronics"
ABSTRACT:

Physicists have used light and its polarization to elucidate the internal state of atoms since the 19th century.  Early in the 20th century, the momentum of light was used to change the center-of-mass motion of atoms.  The latter part of the 20th century brought optical pumping, coherent laser excitation, and laser cooling and trapping as tools to manipulate both the internal and external states of atoms.  Atom optics techniques like diffraction of atoms from light provided the elements needed for atom-wave interferometers.  Bose-Einstein condensation created atomic samples having laser-like deBroglie-wave coherence.   Now, in the 21st century, the circulation of superfluid atoms in ring-shaped structures enables “atomtronic” circuitry—an atomic analog of superconduction electric circuits.  We observe persistent flow of atoms in toroidal traps, and can introduce a weak-link (a kind of Josephson junction) that allows control of the quantized circulation of atoms. 

VIDEO:
ics Special Colloquium


Wednesday, March 1, 2017
3:30 PM
Physics Building, Room 204
Francois Foucart [Host: Peter Arnold]
Lawrence Berkeley National Lab
"From Chirps to Jets: The extreme world of Black Holes and Neutron Stars"
 
 Slideshow (PDF)
ABSTRACT:

Black holes and neutron stars are extraordinary astrophysical laboratories.

They allow us to test the laws of gravity and nuclear physics in extreme environments which cannot be reproduced on Earth. In this talk, I will discuss efforts to model these compact objects in two classes of astrophysical systems: mergers of black hole-neutron star and neutron star-neutron star binaries, and accretion disks around supermassive black holes. The first are powerful sources of gravitational waves, and emit bright electromagnetic transients. In the advanced gravitational wave detector era, they will provide us with new information about general relativity, the properties of matter above nuclear density, and the population of black holes and neutron stars. The second will soon be imaged by the Event Horizon Telescope with enough accuracy to resolve the horizon of two black holes, and to study the behavior of the nearly collisionless plasma accreting onto them. I will in particular focus on the role of numerical simulations using general relativistic codes, which will play a crucial role in our interpretation of these upcoming observations.

 

SLIDESHOW:
ics Special Colloquium


Tuesday, February 28, 2017
3:30 PM
Physics Building, Room 204
Mark Rudner [Host: Israel Klich ]
"Quantum alchemy for the 21st century: accessing new horizons of quantum many-body dynamics through periodic driving"
ABSTRACT:

Recent work on topological materials has revealed a wide variety of intriguing phenomena that may arise when particles move in "non-trivial" bands.  At the same time, modern advances in experimental capabilities for controlling electronic, atomic, and optical systems open new possibilities for dynamically controlling the behaviors of a range of quantum systems. In this talk I will review the basic ideas behind topological band theory, and then explain how periodic driving can be used to gain dynamical control over the topological properties of quantum matter.  In the driven case, intriguing new types of robust non-equilibrium topological phenomena emerge. To illustrate, I will show how the combination of driving, topology, and interactions can bring about a new regime of universal quantized transport, and discuss potential near-term experimental realizations.

**THE RECEPTION WILL BE HELD AT 3:00PM IN ROOM 313**

ics Special Colloquium


Monday, February 27, 2017
3:30 PM
Physics Building, Room 204
Adrian Liu [Host: Peter Arnold]
UC Berkeley
"The Past, Present, and Future of 21cm Cosmology"
 
 Slideshow (PDF)
ABSTRACT:

In the next few years, low-frequency radio telescopes will use the 21cm line of neutral hydrogen to make unprecedentedly large maps of our observable Universe. These will provide exquisite constraints on the properties of the first stars and galaxies. Along these lines, I will review recent results from the Precision Array to Probe the Epoch of Reionization (PAPER) experiment, which have begun to shed light on heating processes in the early universe. I will also discuss how comparing theory and observations will become difficult as one enters the regime of “big data” and theoretical models become increasingly complicated. I will describe how machine learning techniques make such comparisons computationally feasible. Finally, I will discuss the recently commenced Hydrogen Epoch of Reionization Array (HERA) experiment, including its forecasted ability to constrain fundamental parameters such as the neutrino mass. Looking to the future, I will highlight additional opportunities to constrain cosmology and particle physics using the 21cm line.

 

SLIDESHOW:
ics Colloquium
Friday, February 24, 2017
3:30 PM
Physics Building, Room 204
RESERVED
ics Special Colloquium


Thursday, February 23, 2017
3:30 PM
Physics Building, Room 204
Torsten Karzig [Host: Israel Klich ]
Station Q, UCSB
"Progress and challenges in designing a universal Majorana quantum computer"
ABSTRACT:

I will discuss a promising design proposal for a scalable topological quantum computer. The qubits are envisioned to be encoded in aggregates of four or more Majorana zero modes, realized at the ends of topological superconducting wire segments that are assembled into superconducting islands with significant charging energy. Quantum information can be manipulated according to a measurement-only protocol, which is facilitated by tunable couplings between Majorana zero modes and nearby semiconductor quantum dots. The key virtue of the proposed architecture is its modular and scalable design and a natural suppression of quasiparticle poisoning by charge protection.

In the second part of the talk I will comment on the importance of elevating these designs to full quantum universality by so called magic state injection. The latter relies on a high fidelity source of specific quantum states and I will point out some of ideas and challenges for providing them.

**THE RECEPTION WILL BE HELD AT 3:00PM IN ROOM 313**

ics Special Colloquium


Wednesday, February 22, 2017
3:30 PM
Physics Building, Room 204
Michele Vallisneri [Host: Peter Arnold]
Jet Propulsion Laboratory, Caltech
"Gravitational waves from binary black holes across the spectrum"
 
 Slideshow (PDF)
ABSTRACT:

On September 14, 2015, the two LIGO detectors simultaneously observed a transient gravitational-wave signal, which was named GW150914. The signal fit very precisely the general-relativistic prediction for the inspiral, merger, and ringdown of a pair of stellar-mass black holes, with component masses greater than was thought possible in standard evolution scenarios. This was the first direct detection of gravitational waves and the first observation of a binary black-hole merger. I describe the mechanics and behind-the-scenes of the detection, and its implications for astrophysics and fundamental physics. Two additional black-hole binaries were detected in LIGO's first observing run, and more are expected from current data taking. At the low-frequency side of the gravitational-wave spectrum, signals from massive black-hole binaries are targeted by the space-based observatory LISA, now on track for launch in the early 2030s, and by pulsar-timing arrays, with a positive detection expected in ten years. I discuss the science case, prospects, and requirements of these programs.

**THE RECEPTION WILL BE HELD AT 3:00PM IN ROOM 313**

SLIDESHOW:
ics Special Colloquium


Thursday, February 16, 2017
3:30 PM
Physics Building, Room 204
Yi-Zhuang You [Host: Israel Klich ]
Harvard University
"Bosonic Symmetry Protected Topological States: Theory, Numerics, and Experimental Platform"
ABSTRACT:

Topological phases of matter is an active research area of condensed matter physics. Among various topics, the bosonic symmetry protected topological (BSPT) states have attracted enormous theoretical interest in the last few years. BSPT states are bosonic analogs of topological insulators. The Haldane phase of spin-1 chains is one famous example. I will talk about our recent proposal to realize two-dimensional BSPT states in the twisted bilayer graphene with strong magnetic field, as well as numerical simulations of the lattice model in various parameter regimes. The proposed BSPT state is a quantum spin Hall insulator with bosonic boundary modes only. The bosonic modes are spin and charge collective excitations of electrons. The quantum phase transition between the topological and the trivial phases happens by closing the gap of bosonic modes in the bulk, without closing the single particle gap of electrons, which is fundamentally different from all the well-known topological transitions in free fermion topological insulators. On the theory side, the phase transition is related to topics of deconfined criticality and duality of (2+1)D conformal field theories. The theoretical, numerical and experimental studies will deepen our understanding of quantum phase transitions.

**THE RECEPTION WILL BE HELD AT 3:00PM IN ROOM 313**

ics Special Colloquium


Wednesday, February 15, 2017
3:30 PM
Physics Building, Room 204
Kent Yagi [Host: Peter Arnold]
Princeton University
" Probing Extreme Gravity with Black Holes and Neutron Stars"
 
 Slideshow (PDF)
ABSTRACT:

Black holes and neutron stars are extremely compact astrophysical objects that are produced after the death of very massive stars. Due to their large compactness and population, such compact objects offer us excellent testbeds for probing fundamental physics. In this talk, I will focus on probing extreme (strong and dynamical-field) gravity that was previously inaccessible. Regarding black hole based tests of gravity, I will explain how stringently one can probe various fundamental pillars in General Relativity with the recently-discovered gravitational wave events. Regarding neutron star based tests of gravity, I will use approximate universal relations ("I-Love-Q relations") among certain neutron star observables that are almost insensitive to the unknown stellar internal structure, and describe how one can probe extreme gravity by combining future gravitational wave and binary pulsar observations. I will conclude with a summary of important future directions.

SLIDESHOW:
ics Colloquium
Friday, February 10, 2017
3:30 PM
Physics Building, Room 204
Andrey Chubukov [Host: Genya Kolomeisky]
University of Minnesota
"Superconductivity from repulsion"
 
 Slideshow (PDF)
ABSTRACT:

In my talk, I review recent and not so recent works aiming to understand whether a nominally repulsive Coulomb interaction can by itself give rise to a superconductivity.  I discuss a generic scenario of the pairing by electron-electron interaction, put forward by Kohn and Luttinger back in 1965, and  modern studies of  the electronic mechanisms of superconductivity in the lattice systems which model cuprates,  Fe-pnictides, and  doped graphene.  I show that the pairing in all three classes of materials can be viewed as a lattice version of Kohn-Luttinger physics, despite that the pairing symmetries are different.  I discuss under what conditions the pairing occurs and rationalize the need to do  renormalization-group studies.  I also discuss the interplay between superconductivity and density-wave instabilities.

SLIDESHOW:
ics Special Colloquium


Tuesday, February 7, 2017
3:30 PM
Physics Building, Room 204
Renee Horton
NASA
"The Art of Metal Joining and How It's Used NASA Michoud Assembly Facility"
 
 Slideshow (PDF)
ABSTRACT:

Metal joining is a controlled process used to fuse metals. There are several techniques of metal joining of which friction stir welding is one of the more basic forms. Friction stir welding is an innovative weld process that continues to grow in use, in the commercial, defense, and space sectors. It produces high quality and high strength welds in aluminum alloys. The process consists of a rotating weld pin tool that plasticizes material through friction. The plasticized material is welded by applying a high weld forge force through the weld pin tool against the material during pin tool rotation.  Self-reacting friction stir welding (SR-FSW) is one variation of the FSW process developed at the National Aeronautics and Space Administration (NASA) for use in the fabrication of propellant tanks and other areas used on the Space Launch System (SLS)

 

NASA's SLS is an advanced, heavy-lift launch vehicle which will provide an entirely new capability for science and human exploration beyond Earth's orbit. The SLS will give the nation a safe, affordable and sustainable means of reaching beyond our current limits and open new doors of discovery from the unique vantage point of space.

SLIDESHOW:
ics Special Colloquium


Wednesday, February 1, 2017
3:30 PM
Physics Building, Room 204
Anna Ijjas [Host: Peter Arnold]
Princeton University
"Bouncing"
 
 Slideshow (PDF)
ABSTRACT:

In this talk, I will focus on cosmologies that replace the big bang with a big bounce. I will explain how, in these scenarios, the large-scale structure of the universe is determined during a contracting phase before the bounce and will describe the recent development of the first well-behaved classical (non-singular) cosmological bounce solutions.

SLIDESHOW:
ics Colloquium
Friday, January 27, 2017
3:30 PM
Physics Building, Room 204
Available [Host: ]
ics Special Colloquium


Wednesday, January 18, 2017
3:30 PM
Physics Building, Room 204
Ilias Cholis [Host: Peter Arnold]
Johns Hopkins University
"Searching for Dark Matter in Gravitational Waves"
 
 Slideshow (PDF)
ABSTRACT:

The nature of dark matter is one of the most longstanding and puzzling questions in physics. With cosmological measurements we have been able to measure its abundance with great precision. Yet, what dark matter is composed of remains a mystery.

In 2016 the first ever observation of gravitational waves from the coalescence event of two black holes was achieved by the LIGO interferometers.

Together with my collaborators we recently advocated that the interactions of 30 solar masses primordial black holes composing the dark matter could explain this event.

This opens up a new window in indirect searches for dark matter.

In my talk, I will discuss the various probes to distinguish between these mergers of primordial black holes, from the more traditional astrophysical black hole binaries.

One is through their mass spectrum, another is through cross-correlation of gravitational events with future overlapping galaxy catalogs. A third, is through their contribution to the stochastic gravitational wave background. Finally a fourth probe uses the fact that primordial black black holes form binaries with highly eccentric orbits. Those will then merge on timescales that in some cases are years, days or even minutes, retaining some eccentricity in the last seconds before the merger, which can be detected by LIGO and future ground based interferometers.

SLIDESHOW:
ics Colloquium
Friday, December 2, 2016
3:30 PM
Physics Building, Room 203
Eva Andrei [Host: Israel Klich ]
Rutgers University
"Physics of Imperfect Graphene"
ABSTRACT:

Graphene in its pristine form has transformed our understanding of 2D electron systems leading to fundamental discoveries and to the promise of important applications. I will discuss new and surprising phenomena that emerge when the perfect honeycomb lattice of graphene is disrupted. In particular I will focus on the effects of single atom vacancies on graphene's electronic and magnetic properties as revealed by scanning tunneling microscopy and spectroscopy. These include charging the vacancy site into the supercritical regime where we observe the formation of an artificial 2D atom 1,  and electrostatically controlled Kondo screening of the vacancy magnetic moment.

1 J.Mao, Y.Jiang, D. Moldovan,  G. Li,  K. Watanabe, T. Taniguchi,   M. R. Masir, F.M. Peeters, E.Y. Andrei, Tunable Artificial Atom at a Supercritically Charged Vacancy in Graphene, Nature Physics 2016, doi:10.1038/nphys3665

 

ics Colloquium
Friday, November 18, 2016
3:30 PM
Physics Building, Room 203
Marcelle Soares-Santos [Host: Craig Group]
Fermilab
"Physics of the Dark Energy Survey (TBC)"
ABSTRACT:

DES is an ongoing imaging sky survey, the largest such survey to date. Its main science goal is to shed light onto dark energy by making precision measurements of the expansion history and growth of structure in the universe. In this talk I present an overview of our latest results and introduce a new DES initiative: searches for optical counterparts to gravitational wave events.

ics Colloquium
Friday, November 11, 2016
3:30 PM
Physics Building, Room 204

"Available"
ics Special Nobel Lecture


Wednesday, November 9, 2016
7:00 PM
The Paramount, Room The Auditorium
Adam Reiss [Host: Craig Group]
Johns Hopkins University
"The Accelerating Universe"
ABSTRACT:

A public lecture by Adam Reiss, recipient of the 2011 Nobel Prize for the detection of the accelerating expansion of the universe using distant supernovas.  The lecture will be presented at 7 pm on Wednesday, November 9, at the Paramount Theater on Charlottesville's Downtown Mall.

The  Physics  and  Astronomy  Departments  at  the  University  of Virginia in partnership the National Radio Astronomy Observatory invite the community to a special FREE public  lecture  by  Nobel  Laureate  Adam  Riess  at  The  Paramount  Theater  on  Wednesday,  November  9  at 7:00PM.    Prof.  Riess  will  speak  on  the  fascinating  topic  of  the  accelerating  universe.  Due  to  his  critical contributions, Prof. Riess shared the 2011 Nobel Prize "for the discovery of the accelerating expansion of the Universe through observations of distant supernovae."  The term "supernovae" refers to stars exploding at the end of their lives. The team Prof. Riess worked with used a particular kind of supernova, called type Ia supernova,  to  understand  the  properties  of  distant  galaxies.    His  research  team  found  that  light  from distant  supernovae  was  weaker  than  expected  ‐  this  was  a  sign  that  the  expansion  of  the  Universe  was accelerating. Prof. Riess will discuss the excitement of this discovery, its implications, and current ongoing work to help answer remaining questions. 

https://conference.phys.virginia.edu/indico/event/1/page/14-the-accelerating-universe-public-lecture-by-nobel-laureate-adam-riess

 

ics Colloquium
Friday, November 4, 2016
3:30 PM
Physics Building, Room 204

"Available"
ics Colloquium
Friday, October 28, 2016
3:30 PM
Physics Building, Room 204

"Available"
ics Colloquium
Friday, October 21, 2016
3:30 PM
Physics Building, Room 204

"Available"
ics Colloquium
Friday, October 14, 2016
3:30 PM
Physics Building, Room 204

"Available"
ics Colloquium
Friday, October 7, 2016
3:30 PM
Physics Building, Room 204

"Available"
ics Colloquium
Friday, September 30, 2016
3:30 PM
Physics Building, Room 204
Samir Mathur [Host: Peter Arnold]
Ohio State
"Resolution of the black hole information paradox"
 
 Slideshow (PDF)
ABSTRACT:

Some 40 years ago Hawking found a remarkable contradiction: if we accept the standard behavior of gravity in regions of low curvature, then the evolution of black holes will violate quantum mechanics. Resolving this paradox would require a basic change in our understanding of spacetime and/or quantum theory. This paradox has found an interesting resolution through string theory. While quantum gravity is normally expected to be important only at distances of order planck length, the situation changes when a large number N of particles are involved, as for instance in the situation where we make a large black hole. Then the length scale of quantum gravity effects grows with N, altering the black hole structure to a "fuzzball"; this effect resolves the paradox.

SLIDESHOW:
ics Colloquium
Friday, September 23, 2016
3:30 PM
Physics Building, Room 204
Aron Bernstein [Host: Gordon Cates]
MIT
"Nuclear Weapons: Sources of Strength or Vulnerability? "
ABSTRACT:

An objective overview of the nuclear arms race will be presented with an emphasis  on the present situation. A brief sketch of how nuclear weapons work and some ironic lessons from history will be presented. Scientists' discussions about preventing proliferation and use started in the secrecy of the Manhattan Project and continued in public during the rapid cold war buildup to the present (e.g., Bulletin of the Atomic Scientists). The central role of the nuclear non-proliferation treaty, the Iran agreement, possible pathways to nuclear conflict, and a personal view of the outlook to prevent future nuclear weapons use, including the vital role of education, will be presented.

 Aron Bernstein is Professor of Physics, Emeritus, MIT. His physics research has focused on experimental tests of the symmetries of the standard model (chiral anomaly and symmetry). He has followed the nuclear arms race carefully since the Cuban Missile Crisis, has taught courses on this subject, and has done research on arms control issues such as the dangers posed by the Russian and US short ballistic missile launch and warning times. He is a National Board Member of the Council for a Livable World, started by physicist Leo Szilard, which works with Congress on nuclear arms control issues.

ics Colloquium
Friday, September 16, 2016
3:30 PM
Physics Building, Room 204
Graduate Town Hall Meeting
ics Colloquium
Friday, September 9, 2016
3:30 PM
Physics Building, Room 204

"Available"
ics Colloquium
Friday, September 2, 2016
3:30 PM
Physics Building, Room 204

"Available"
ics Colloquium
Friday, August 26, 2016
3:30 PM
Physics Building, Room 204
Tim Gay [Host: Xiaochao Zheng]
University of Nebraska
"Electron Circular Dichroism and the Origin of Life On Earth"
 
 Slideshow (PDF)
ABSTRACT:

We have bombarded chiral halocamphor molecules in the gas phase with low-energy (< 1 eV), longitudinally-spin-polarized electrons, and investigated dissociative electron attachment (DEA) reactions:

e- + HA → H- + A,

where H is a halogen atom (Br or I) and A is the residual camphor fragment.  We observe that for a given target handedness, the total DEA cross section depends on the helicity of the incident electron.  In the case of iodocamphor at the lowest incident electron energies, this effect can be as large as two parts in 1000.  The observation of chiral sensitivity in a break-up reaction is important because, among other things, it validates the premise of the Vester-Ulbricht hypothesis regarding the origins of biological homochirality.  The sordid history of previous attempts to demonstrate such effects will be briefly reviewed.

SLIDESHOW:
ics Colloquium
Monday, May 2, 2016
3:30 PM
Physics Building, Room 203
Peter Shawhan [Host: Peter Arnold]
University of Maryland
"The Remarkable Story of LIGO's Detection of Gravitational Waves"
 
 Slideshow (PDF)
ABSTRACT:

On February 11, LIGO scientists announced the direct detection of gravitational waves, confirming a century-old prediction of Einstein's general theory of relativity.  This milestone was finally made possible with the incredibly sensitive Advanced LIGO detectors, combined with a certain measure of luck. This first event is already enough to investigate the properties of the source, test the theory of gravity, and project what more we can learn from future events.  I will share both the scientific meaning of the discovery and some of the personal stories behind it.

VIDEO:
ics Colloquium
Friday, April 29, 2016
3:30 PM
Physics Building, Room 204
David Tanner [Host: Seunghun Lee]
University of Florida
"30 years of high Tc: Superfluid and normal-fluid densities in the cuprate superconductors"
 
 Slideshow (PDF)
ABSTRACT:

It was in April 1986 when Bednorz and Mueller of the IBM Zürich laboratories sent a paper about “possible high-Tc superconductivity” to Zeitschrift für Physik B.  The resulting bombshell changed condensed-matter physics forever.  Experimenters and theorists developed methods to measure and calculate in ways that were much improved over prior years. However, despite 30 years of intense study, the description of these materials remains incomplete. I’ll discuss the  discovery of the high Tc cuprates from the perspective of a participant.  I’ll then turn to what infrared spectroscopy can tell us about their properties. Measurements for a number of cuprate families of optical reflectance over a wide spectral range (far-infrared to ultraviolet) have been analyzed using Kramers-Kronig analysis to obtain the optical conductivity, s(w), and (by integration of the real part of the conductivity) the spectral weight of low- and mid-energy excitations. For the Kramers-Kronig analysis to give reliable results, accurate high-frequency extrapolations, based on x-ray atomic scattering functions, were used. When the optical conductivities of the normal and superconducting states are compared, a transfer of spectral weight from finite frequencies to the zero-frequency delta-function conductivity of the superconductor is seen. The strength of this delta function gives the superfluid density, rs. There are two ways to measure rs, using either the low energy spectral weight or by examination of the imaginary part, s2(w); both estimates show that 98% of the ab-plane superfluid density comes from low energy scales, below about 0.15 eV. Moreover, there is a notable difference between clean metallic superconductors and the cuprates.  In the former, the superfluid density is essentially equal to the conduction electron density. The cuprates, in contrast, have only about 20% of the ab-plane low-energy spectral weight in the superfluid. The rest remains in finite-frequency, midinfrared absorption. In underdoped materials the superfluid fraction is even smaller. The consequences of this observation for the electronic structure will be addressed.

SLIDESHOW:
ics Colloquium
Friday, April 22, 2016
3:30 PM
Physics Building, Room 204
Boris Shklovskii [Host: Eugene Kolomeisky]
Univ. Minnesota
"How many electrons make a semiconductor nanocrystal film metallic? "
ABSTRACT:

Films of semiconductor nanocrystals are used as a novel, low-cost electronic materials for optoelectronic devices. To achieve their full potential a better understanding of their conductivity as a function of concentration of donors is required. So far, it is not known how many donors will make a nanocrystal film metallic. In bulk semiconductors, the critical concentration of electrons at the metal-insulator transition is universally described by the famous Mott criterion. We show theoretically that in a dense NC film, where NCs touch each other by small facets with radius r << d, the critical concentration of electrons N at the metal-insulator transition satisfies the condition is given by N r^3 = 1.
This critical concentration is typically 100 times larger than the Mott one. In the accompanying experiments, we investigate the conduction mechanism in films of phosphorus-doped silicon nano-crystals. At the largest electron concentration achieved in our samples, which is half the predicted N, we find that the localization length of hopping electrons is close to three times the nano-crystals diameter, indicating that the film approaches the metal-insulator transition.

ics Colloquium
Friday, April 15, 2016
3:30 PM
Physics Building, Room 204
Anatoly Kolomeisky [Host: Israel Klich ]
Rice University
"How to Understand Molecular Transport through Channels: The Role of Interactions"
 
 Slideshow (PDF)
ABSTRACT:

The motion of molecules across channels and pores is critically important for understanding mechanisms of many biological, chemical, physical and industrial processes. Here we investigate the role of different types of interactions in the channel-facilitated molecular transport by analyzing exactly solvable discrete-state stochastic models. According to this approach, the channel transport is a non-equilibrium process that can be viewed as a set of coupled quasi-chemical transitions between discrete spatially separated states. It allows us to obtain a full dynamic description of the translocation via the pore, clarifying many aspects of these complex processes. We show that the strength and the spatial distribution of the molecule/channel interactions can strongly modify the particle fluxes through the system. Our analysis indicates that the most optimal transport is achieved when the binding sites are near the entrance or near the exit of the pore, depending on the sign of the interaction potentials. These observations allow us to explain current single-molecule experiments on the translocation of polypeptides through biological channels. We also suggest that the intermolecular interactions during the channel transport might significantly influence the overall translocation dynamics. Our explicit calculations show that the increase in the flux can be observed for some optimal interaction strengths. But the flux can also be fully suppressed for some conditions. The relevance of these results for biological systems is discussed. The physical-chemical mechanisms of these phenomena are analyzed from the microscopic point of view.

SLIDESHOW:
ics Special Colloquium: Hoxton Lecture


Thursday, April 14, 2016
7:00 PM
Chemistry Building, Room 402
Sidney R. Nagel [Host: Seunghun Lee]
University of Chicago
"Impact and Intrusion: the surprises and elegance of how nature arranges the texture of our lives"
 
 Slideshow (PDF)
ABSTRACT:

Many complex phenomena are so familiar that we hardly realize that they defy our normal intuition.  Examples include the anomalous flow of granular material, the long messy tendrils left by honey spooned from one dish to another, the pesky rings deposited by spilled coffee on a table after the liquid evaporates or the common splash of a drop of liquid onto a countertop.  Aside from being uncommonly beautiful to see, many of these phenomena involve non-linear behavior where the system is far from equilibrium.  Although most of the world we know is beyond description by equilibrium theories, we are still only at the threshold of learning how to deal with such deep and complex behavior.  Thus, these are phenomena that can lead the inquisitive into new realms of physics.

SLIDESHOW:
ics Joint Physics-Astronomy Colloquium


Friday, April 8, 2016
3:30 PM
Physics Building, Room 204
Isaac Shlosman [Host: Eugene Kolomeisky]
University of Kentucky
"Seeds of Supermassive Black Holes at High Redshifts"
ABSTRACT:

Detection of distant quasars at redshifts of ~6-7 provides a challenge to the standard picture of structure formation in the universe within the hierarchical framework, as the universe is less than a Gigayear old at this time. What are seeds of supermassive black holes (SMBHs) that power these luminous objects? After all,  massive objects should form late in the evolution ...  Did  SMBHs form as a result of stellar evolution? In my talk, I will address various aspects of this problem and discuss viable and emerging alternatives to this paradigm.

ics Colloquium
Friday, April 1, 2016
3:30 PM
Physics Building, Room 204
Neil Zimmerman [Host: Jongsoo Yoon]
NIST
"Do Electrons in a Metal Have the Same Charge as Free Electrons in Vacuum?"
 
 Slideshow (PDF)
ABSTRACT:

At NIST, we have the enjoyable jobs of combining i) state-of-the-art research with ii) the fascinating search for higher and higher accuracy measurements.  In this talk, I will i) introduce the SI system of units and explain why devices that can move around single electrons one-by-one are of great interest, ii) give an introduction to the nanoelectronic devices known as single electron transistors and pumps, iii) describe a high-accuracy measurements of the charge of electrons in a metal, and iv) discuss the possibility that this charge is not the same as the charge of a free electron in vacuum.

SLIDESHOW:
ics Colloquium
Thursday, March 31, 2016
9:45 AM
Wilsdorf Hall, Room 200
Ian Anderson [Host: Despina Louca]
ORNL
"Opportunities for Collaboration at Oak Ridge National Laboratory"
ics Colloquium
Friday, March 25, 2016
3:30 PM
Physics Building, Room 204
Prof. Chia Ling Chien [Host: Seunghun Lee]
Johns Hopkins University
"Golden Era of Modern Magnetism "
ABSTRACT:

Magnetism has been an old subject dating back to antiquity.  Few could envision that modern magnetism would enter a golden era with the realization of so many new phenomena and game-changing technologies.  These remarkable advances are due to spin ½ of electrons, as illustrated in this talk through several recent examples, including pure spin current phenomena, skyrmion materials, and p-wave superconductivity.

ics Colloquium
Thursday, March 24, 2016
7:30 PM
Maury Hall, Room 209
Alice Bowman and Anne Verbiscer [Host: UVA Physics and Astronomy Departments]
"Rediscovering Pluto: a panel on NASA's recent Pluto Mission (New Horizons)"
ABSTRACT:

On July 14, 2015, New Horizons, an interplanetary space probe, flew by Pluto, capturing the first high resolution photographs of Pluto’s surface and atmosphere. New Horizons data has revealed stunning geology including ice volcanoes, Nitrogen ice glaciers, mysterious internal heating, and the “snakeskin” patterns among 50 other discoveries. UVA’s planetary astronomer, Anne Verbiscer, will describe Pluto’s amazing science phenomena, and Alice Bowman will explain the missions and engineering side of New Horizons sharing her experience as New Horizons’ MOM. This event is meant for the general public, and everyone is invited. A reception will follow the talk.

 

Sponsored by UVA Physics and Astronomy Departments.
Organized by Astronomical Society at UVA and SPS

A map showing the location of Maury Hall is available online at the following address:
http://www.virginia.edu/webmap/popPages/55-MauryHall.html

ics Colloquium
Friday, March 18, 2016
3:30 PM
Physics Building, Room 204
Alex Cronin [Host: Cass Sackett]
University of Arizona
"Atom Interferometry Measurements of Atomic Polarizabilities and Tune-out Wavelengths"
 
 Slideshow (PDF)
ABSTRACT:

Atom interferometry, in which de Broglie waves of matter are coherently split and later recombined to make interference fringes, is a precision measurement method with applications in many fields of physics.  In Arizona, we measured the ground-state static electric-dipole polarizabilities of Cs, Rb, and K atoms with 0.2% uncertainty using an atom beam interferometer.  We also measured a tune-out wavelength for K atoms with sub-picometer uncertainty.  I will discuss how these experiments use electric field gradients to induce polarizability-dependent phase shifts for atomic de Broglie waves. Our measurements provide benchmark tests for atomic structure calculations and thus test the underlying theory used to predict van der Waals forces and to interpret atomic parity non-conservation experiments.

SLIDESHOW:
ics Colloquium
Friday, March 4, 2016
3:30 PM
Physics Building, Room 204
Michael Chertkov [Host: Marija Vucelja]
LANL
"Physics Informed Machine Learning"
ABSTRACT:

Machine Learning (statistical engineering) capabilities are in a phase of tremendous growth. Underlying these advances is a strong and deep connection to various aspects of statistical physics. There is also a great opportunity in pointing these tools toward physical modeling. In this colloquium I  illustrate the two-way flow of ideas between physics and statistical engineering on three examples from our team LANL. First, I review the work on  structure learning and statistical estimation in power system distribution (thus physical) networks. Then I describe recent progress in constructive understanding of graph learning (on example of inverse Ising model) illustrating that the generic inverse task (of learning) is computationally easy in spite of the fact that the direct problem (inference or sampling) is difficult. I conclude speculating how macro-scale models of physics (e.g. large eddy simulations of turbulence) can be learned from micro-scale simulations (e.g. of Navier-Stocks equations).

https://sites.google.com/site/mchertkov/

ics Colloquium
Friday, February 26, 2016
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, February 19, 2016
3:30 PM
Physics Building, Room 204
Bellave Shivaram [Host: Vittorio Celli]
University of Virginia - Physics Dept.
"Metamagnetism - its ubiquity and universality"
ABSTRACT:

The emergent universality in the nonlinear magnetic response of itinerant metamagnets will be discussed. Recent experimental work on heavy fermions, Hunds metals, and single molecule magnets will be presented. The appeal of the ‘single energy scale model’ developed in the context of these new measurements [(a) "Universality in the Nonlinear Magnetic Response of Strongly Correlated Metals", B.S. Shivaram, D.G. Hinks, M.B. Maple and P. Kumar, Phys. Rev., B89, 241107(Rapid Communication), 2014. [b] "Metamagnetism and the Fifth Order Susceptibility in UPt3", B.S. Shivaram, Brian Dorsey, D.G. Hinks and Pradeep Kumar, Phys. Rev., B89, 161108(Rapid Communication), (2014). [c] “High Field Ultrasound Measurements in UPt3 and the Single Energy Scale Model of Metamagnetism”, B.S. Shivaram, V.W. Ulrich, P. Kumar and V. Celli, Phys. Rev.B, 91, 115110, 2015] will be critically examined.

ics Colloquium
Friday, February 12, 2016
3:30 PM
Physics Building, Room 204
Talat Rahman [Host: Vittorio Celli]
University of Central Florida
"Tailoring properties of single and bilayer layer transition metal dichalcogenides: looking beyond graphene*"
 
 Slideshow (PDF)
ABSTRACT:

Single-layer of molybdenum disulfide (MoS2) and other transition metal dichalcogenides appear to be promising materials for next generation nanoscale applications (optoelectronic and catalysis), because of their low-dimensionality, intrinsic direct band-gap which typically lies in the visible spectrum, and strikingly large binding energies for excitons and trions. Several experimental groups have already reported novel electronic and transport properties which place these material beyond graphene for device applications. MoS2 is also known to be a leading hydrodesulphurization catalyst. Efforts are underway to further tune these properties through alloying, defects, doping, coupling to a substrate, and formation of bilayer stacks (homo- and hetero-structures).  In this talk I will present results [1-3] which provide a framework for manipulating the functionality of these fascinating materials and take us closer to the goal of rational material design.  My emphasis will be on properties of pure and defect-laden single layer MoS2 with and without underlying support.  I will also provide rationale for the differences in the excitation energetics and ultrafast charge dynamics in single and bilayer (hetero and homo) dichalcogenides.

[1] D. Sun, et al., “An MoSx Structure with High Affinity for Adsorbate Interaction,” Angew. Chem. Int. Ed. 51, 10284 (2012).

[2] D. Le, T. B. Rawal, and T. S. Rahman, “Single-Layer MoS2 with Sulfur-Vacancies: Structure and Catalytic Application,” J. Phys. Chem. C 118, 5346 (2014).

[3] A. Ramirez-Torres, V.Turkowski, and T. S. Rahman, “Time-dependent density-matrix functional theory for trion excitations: application to monolayer MoS2,” Phys. Rev. B 90, 085419 (2014).

SLIDESHOW:
ics Colloquium
Friday, February 5, 2016
3:30 PM
Physics Building, Room 203
Michael Mann [Host: GPSA]
Pennsylvania State Univ.
"The Physics of Climate Change"
 
 Slideshow (PDF)
ABSTRACT:

I will review the basic underlying science of climate and climate change, including physically-based models of Earth's climate. I will motivate the use of a simple, zero-dimensional "Energy Balance Model" of Earth's radiative balance that can be used to estimate the global mean surface temperature of Earth. I will show how this model successfully reproduces the observed historical changes in global temperature, and how it can be used to assess various questions about future human-caused climate change.

 

VIDEO:
ics Colloquium
Friday, January 29, 2016
3:30 PM
Physics Building, Room 204
Fred Olness [Host: Simonetta Liuti]
Southern Methodist University
"Things that go bump in the data: QCD Puzzles, Predictions, and Prognoses"
 
 Slideshow (PDF)
ABSTRACT:

The very successful Run I of the Large Hadron Collider (LHC) culminated in the discovery of the Higgs boson which was the subject of the 2013 Nobel Prize.

How will we know if there are other "undiscovered" particles in the data? (And, was there a hint from CERN last month???)  This will require improved calculations, and the key ingredients are:

i) higher-order theoretical cross section calculations, and

ii) precise Parton Distribution Functions (PDFs) that characterize the proton structure.

 

Surprisingly, these predictions are influenced by a wide range of data including precision low-energy nuclear results. Recent theoretical developments improve our ability to address the QCD multi-scale problem and higher orders across the full kinematic range.

 

We look at some of the topics, puzzles, and challenges that lie on the horizon, and identify areas where additional efforts are required.

SLIDESHOW:
ics Colloquium: Cancelled due to snow


Friday, January 22, 2016
3:30 PM
Physics Building, Room 204
Olivier Pfister [Host: Seunghun Lee]
UVA-Physics
"Building a quantum computer from the top down: massive-scale entanglement in the quantum optical frequency comb"
ABSTRACT:

Quantum computing offers revolutionary promises of scientific and societal importance, based on its exponential speedup of particular tasks: on the one hand, Richard Feynman's quantum simulator would allow us to tackle currently intractable quantum chemistry problems (nitrogen fixation, carbon sequestration) as well as quantum physics ones (high-Tc superconductivity); on the other hand, Peter Shor's algorithm for factoring integers would render RSA encryption obsolete.

 

Building a practical quantum computer demands that one address the challenges of decoherence and scalability. While the platforms of trapped-ion qubits and of superconducting qubits have made spectacular progress in the fight against decoherence, our approach has been to tackle scalability, in particular by discovering a new “top down,” rather than “bottom up,” method for generating the entangled states, or "cluster" states, that enable the particular flavor of quantum computing called measurement-based, or one-way, quantum computing.  

 

Our method uses the continuous variables of light — “qumodes,” rather than qubits — defined by the quadrature amplitudes of the quantized electromagnetic field emitted over the cavity modes, or quantum optical frequency comb, of a single optical parametric oscillator. We demonstrated a world-record cluster state size of 60 entangled qumodes (3 × 103 in progress), all simultaneously available in the frequency domain. I will also present our new proposal for generating cluster states of unlimited size by using both the time and frequency degrees of freedom.

ics Colloquium
Friday, December 4, 2015
3:30 PM
Physics Building, Room 204
Charles Hyde [Host: Simonetta Liuti]
Old Dominion University
"Spatial Imaging of Quarks and Gluons in the Proton"
 
 Slideshow (PDF)
ABSTRACT:

For many years, it was generally thought that spatial imaging of the proton was impossible in principle, due to the relativistic recoil of the proton when ever it is probed at momentum scales of order of the inverse of the proton size.  Two decades ago, a new set of QCD matrix elements were defined, called Generalized Parton Distributions (GPDs), that encode the spatial distributions of quarks and gluons transverse to a preferred momentum axis.  It was independently discovered that the GPDs are accessible experimentally in Deep Virtual Exclusive reactions:  high energy reactions of the type e p —> e p gamma.

I will review the progress of experimental efforts to measure GPDs, and discuss the extent to which spatial distributions can be extracted from present and future data.

SLIDESHOW:
ics Colloquium
Friday, November 20, 2015
3:30 PM
Physics Building, Room 204
Chang Kee Jung [Host: Seunghun Lee]
SUNY at Stony Brook
"Discovery of Electron Neutrino Appearance from a Muon Neutrino Beam in T2K and Future Outlook for Discovery of CP Violation in Lepton Sector in DUNE at LBNF"
ABSTRACT:

Matter-antimatter asymmetry is one of the most outstanding mysteries of the universe that provides a necessary condition to our own existence. There have been various attempts to solve this mystery including 'Baryogenesis' hypothesis. However, the B-factory experiments during the last decade showed that the observed CP-violation (CPV) in the quark sector is not big enough for baryogenesis to be a viable solution to the matter-antimatter asymmetry. This leads us to the 'Leptogenesis' hypothesis, in which CPV in the lepton section plays a crtical role to create the matter-antimater asymmetry at the onset of the Big Bang. Thus, experimental observation of CPV in the lepton sector could prove to be tantamount to one of the most important discoveries in our understanding of the universe.

In 2011, the T2K experiment published a result that provided the first indication for a non-zero $\theta_{13}$, the last unknown mixing angle in the lepton sector at that time, at 2.5 sigma level of significance. In 2013, after analyzing two more years of data taken since 2011, the experiment reported "Observation of electron neutrino appearance from a muon neutrino beam" at 7.3 sigma level of significance. While neutrino oscillation has been well-established since the discovery by the Super-Kamiokande experiment in 1998, there have not been a definitive observation of neutrino oscillation in a so-called "appearance mode", and this new T2K observation is the first time an explicit neutrino flavor (electron) appearance is observed from another neutrino flavor (muon). This observation also opens the door to study CPV in neutrinos. When incorporating recent precision measurements on $\theta_{13}$ by the reactor experiments along with other neutrino oscillation parameter measurements, T2K data show an intriguing initial result on the $\delta_{CP}$, which is further corroborated by the Super-Kamiokande atmospheric neutrino results as well as the most recent results from NOvA.

Ultimately, however, in order to establish unequivocal results on leptonic CPV, we need a next generation experiment with a more powerful beam, and a larger and/or higher resolution detector. The Deep Underground Neutrino Experiment (DUNE) in US that is newly established as a truly international collaboration, is such an experiment. Physics goals of DUNE include: discovery of CPV in the lepton sector, detrmination of mass hierarchy, discovery of proton decay and observation of neutrinos from the Type-II supernovae. In this talk I will introduce the rapidly developing DUNE experiment and the collaboration, and also discuss possible opportunities for participation.

I will also briefly comment on the Nobel Prize in Physics 2015 as well as The Breakthrough Prize in Fundamental Physics 2016 that were given to the
neutrino oscillation experiments.

ics Colloquium
Friday, November 13, 2015
3:30 PM
Physics Building, Room 204
Jackie Krim [Host: Joe Poon]
North Carolina State University
"Friction, magnetism and superconductivity: Are they interrelated?"
 
 Slideshow (PDF)
ABSTRACT:

Studies of the fundamental origins of friction have undergone rapid progress in recent years with the development of new experimental and computational techniques for measuring and simulating friction at atomic length and time scales.  The increased interest has sparked a variety of discussions and debates concerning the nature of the atomic-scale and quantum mechanisms that dominate the dissipative process by which mechanical energy is transformed into heat.  Measurements of the sliding friction of physisorbed monolayers and bilayers in gaseous and liquid enviroments provide information on the relative contributions of electronic, magnetic, electrostatic and phononic dissipative mechanisms. The experiments will be discussed within the context of current theories of how friction originates at the atomic scale.

SLIDESHOW:
ics Colloquium
Friday, November 6, 2015
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, October 30, 2015
3:30 PM
Physics Building, Room 204
Mark Robbins [Host: Seunghun Lee]
Johns Hopkins University
"A “Rough” View of Friction and Adhesion"
ABSTRACT:

Friction affects many aspects of everyday life and has played a central role in technology dating from the creation of fire by rubbing sticks together to current efforts to make nanodevices with moving parts. The friction "laws" we teach today date from empirical relationships observed by da Vinci and Amontons centuries ago. However, understanding the microscopic origins of these laws remains a challenge. While Amontons said area was proportional to load and independent of area, most modern treatments assume that friction is proportional to the real area of contact where atoms on opposing surfaces are close enough to repel. Calculating this area is complicated because elastic interactions are long range and surfaces are rough on a wide range of scales. In many cases they can be described as self-affine fractals from nanometer to millimeter scales. The talk will first show that this complex problem has a simple solution. Dimensional analysis implies a linear relation between real contact area and load that can explain both Amontons' laws and many exceptions to them. Next the talk will explain why we can't climb walls like spiderman even though the attractive interactions between atoms on our finger tips should provide enough force to support our weight. The talk will conclude by considering how forces in the contact area give rise to friction. Friction shows surprisingly counterintuitive and complex behavior in nanometer to micrometer scale contacts and only a few explanations are consistent with macroscopic measurements.

ics Colloquium
Friday, October 23, 2015
3:30 PM
Physics Building, Room 204
Brooks Pate [Host: Thomas Gallagher]
UVA - Chemistry
"Broadband Molecular Rotational Spectroscopy for Chemical Dynamics and Molecular Structure"
 
 Slideshow (PDF)
ABSTRACT:

Until about 2005, molecular rotational spectroscopy was performed using narrowband (~1 MHz) excitation of a low-pressure gas in a resonant cavity.  This method offers high sensitivity for each data acquisition, but the time required to perform a spectrum scan over about 10 GHz, needed to capture the rotational spectrum, was a major limitation to applications of the technique.  Advances in high-speed digital electronics have made it possible to design spectrometers that offer instantaneous, broadband (> 10 GHz) performance.  During our initial work with high-speed arbitrary waveform generators and digitizers (with Tom Gallagher) we developed the method of chirped pulse Fourier transform rotational spectroscopy that uses a pulse with linear chirp to phase-reproducibly excite the gas sample.  The subsequent coherent emission (free induction decay) is detected with the high-speed digitizer and the frequency domain spectrum is obtained using FFT analysis.  Since the introduction of the technique in 2008 [1], the method has been applied to unimolecular reaction dynamics [2], the structures of molecular clusters [3], and the laboratory identification of molecules in the interstellar medium [4].  The technique has been extended to mm-wave spectroscopy with applications to Rydberg spectroscopy [5], chemical reaction dynamics, and analytical chemistry.  The broadband technique has also enabled a new generation of molecular structure studies in the field of chirality [6] with the potential for solving significant challenges for real-time pharmaceutical manufacturing.

 

References

[1] G.G. Brown, B.C. Dian, K.O. Douglass, S.M. Geyer, and B.H. Pate, “A Broadband Fourier Transform Microwave Spectrometer Based on Chirped Pulse Excitation” Rev. Sci. Instrum. 79, 053103 (2008).

[2] B.C. Dian, G.G. Brown, K.O. Douglass, and B.H. Pate, “Measuring Picosecond Isomerization Dynamics via Ultra-broadband Fourier Transform Microwave Spectroscopy”, Science 320, 924-928 (2008).

[3] C. Pérez, M.T. Muckle, D.P. Zaleski, N.A. Seifert, B. Temelso, G.C. Shields, Z. Kisiel, and B.H. Pate, “Structures of Cage, Prism, and Book Isomers of Water Hexamer from Broadband Rotational Spectroscopy”, Science 336, 897-901 (2012).

[4] D.P. Zaleski, N.A. Seifert, A.L. Steber, M.T. Muckle, R.A. Loomis, J.F. Corby, O. Martinez, Jr., K.N. Crabtree, P.R. Jewell, J.M. Hollis, F.J. Lovas, D. Vasquez, J. Nyiramahirwe, N.  Sciortino, K. Johnson, M.C. McCarthy, A.J. Remijan, and B.H. Pate, “Detection of E-cyanomethanimine towards Sagittarius B2(N) in the Green Bank Telescope PRIMOS Survey”, Ap. J. Letters, 765, L10 (2013).

[5] K. Prozument, A.P. Colombo, Y. Zhou, G.B. Park, V.S. Petrovic, S.L. Coy, and R.W. Field, “Chirped-pulse Millimeter-wave Spectroscopy of Rydberg-Rydberg Transitions”, Phys. Rev. Lett. 107, 143001 (2011).

[6] D. Patterson, M. Schnell, and J.M. Doyle, “Enantiomer-specific detection of chiral molecules via microwave spectroscopy”, Nature 497, 475 (2013).

SLIDESHOW:
ics Colloquium
Friday, October 16, 2015
3:30 PM
Physics Building, Room 204
Thomas Katsouleas [Host: Joseph Poon]
Provost and Department of Physics UVA
"Surfing on a Plasma Wave - Can a Grand Challenge for Engineering Answer the Big Questions of Physics?"
 
 Slideshow (PDF)
ABSTRACT:

The National Academy of Engineering has identified 14 Grand Challenges for Engineering for the 21st Century, spanning human needs from sustainability to security, health and joy of living.  The last category includes such topics as engineering the tools of scientific discovery. This talk will include a brief review of the NAE Grand Challenges and the response of higher education to the Challenges, and will conclude with a review of one Grand Challenge topic:  the development of ultra-compact particle accelerators based on surfing at (nearly) the speed of light on waves created by lasers or particle beams in a plasma gas. The prospects of these devices as tools of scientific discovery as well as beam therapy will be discussed.

VIDEO:
ics Colloquium
Friday, October 9, 2015
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, October 2, 2015
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, September 25, 2015
3:15 PM
Physics Building, Room 204
Adrian Feiguin [Host: Israel Klich ]
Northeastern University
"Iron Chef: recipes for building magnetic structures atom by atom"
 
 Slideshow (PDF)
ABSTRACT:

Understanding Magnetism is a complex undertaking: it relies on our knowledge of the exact position of magnetic ions in a crystal and their interactions. More important, at its core, this is fundamentally a quantum problem and requires understanding the cooperative effects of many degrees of freedom. In the past decade, we have witnessed enormous progress in experiments that consist of placing magnetic atoms at predetermined positions on substrates, and building magnetic nanostructures, one atom at a time. The electrons in the substrate mediate the interactions between the spins, and scanning tunneling microscopy allows one to study their properties.

 

In order to understand these interactions, we rely on a theory developed decades ago by Ruderman, Kittel, Kasuya, and Yosida, dubbed "RKKY Theory", which applies when the spins are classical. The quantum nature of the electronic spin introduces more complexity, and competition with another quantum phenomena: the Kondo effect. The combined effect is non-trivial, and can only be studied by numerical means.  I will describe this effect by introducing an exact mapping onto an effective one-dimensional problem that we can solve with the density matrix renormalization group method (DMRG). I will also show that for dimension d>1, Kondo physics dominates even at short distances, while the ferromagnetic RKKY state is energetically unfavorable. This may have important implications for our understanding of heavy fermion materials and magnetic semiconductors.

SLIDESHOW:
ics Colloquium
Friday, September 18, 2015
3:30 PM
Physics Building, Room 204
Craig Group [Host: Joe Poon]
University of Virginia
"Hoos at Fermilab"
ABSTRACT:

I will review the current status of the Mu2e and NOvA experiments at Fermilab.  These experiments hope to shed light on several important topics in particle physics:  neutrino oscillations, lepton flavor, the matter/antimatter asymmetry of the Universe, dark matter, and others.   As I describe the status and goals of these experiments I will highlight the impact of our UVA efforts. 

ics Colloquium
Friday, September 11, 2015
3:30 PM
Physics Building, Room 204
Seung-Hun Lee [Host: Joe Poon]
UVA-Physics
"Love triangles, quantum fluctuations and spin jam "
ABSTRACT:

When magnetic moments are interacting with each other in a situation resembling that of complex love triangles, called frustration, a large set of states that are energetically equivalent emerge. This leads to exotic spin states such as spin liquid and spin ice. In their paper recently published in the Proceedings of the National Academy of Sciences (PNAS), we presented evidence for the existence of a topological glassy state, that we call a spin jam, induced by quantum fluctuations. The case in point is SrCr9pGa12-9pO19 (SCGO(p)), a highly frustrated magnet, in which the magnetic Cr ions form a quasi-two-dimensional triangular system of bi-pyramids. This system has been an archetype in search for exotic spin states. Understanding the nature of the state has been a great intellectual challenge. Our new experimental data and theoretical spin jam model provide for the first time a coherent understanding of the phenomenon. Furthermore, the findings strongly support the possible existence of purely topological glassy states.

ics  Special Colloquium: INPP Annual Lecture


Monday, April 27, 2015
3:30 PM
Physics Building, Room 203
Stanley J. Brodsky [Host: Dinko Pocanic]
SLAC, Stanford University
"The Novel World of Hadron Physics"
 
 Slideshow (PDF)
ABSTRACT:

I will survey a number of exciting new developments in hadron physics.

These include: new insights into the nature of the color-confi ning con finement quark potential in quantum chromodynamics; a novel application of supersymmetry to hadron physics; the relation between the parameter ΛMS which controls high-energy interactions of quarks to the mass of the proton; and the elimination of the renormalization scale ambiguity for perturbative QCD calculations.

I will also discuss several novel experimental tests of QCD which can be performed at JLab, including: hard exclusive and diff ractive reactions, flavor-dependent antishadowing of nuclear interactions; intrinsic strange- and charm-quark phenomena; the production of tetraquarks and other exotic hadronic states; and factorization-breaking lensing phenomena.

SLIDESHOW:
ics  OSA & SPIE joint Student Chapter at UVA


Friday, April 24, 2015
3:30 PM
Physics Building, Room 204
Jun Ye [Host: Olivier Pfister]
JILA, National Institute of Standards and Technology, University of Colorado
"Ultracold molecules – a new frontier for quantum physics and chemistry"
 
 Slideshow (PDF)
ABSTRACT:

Molecules cooled to ultralow temperatures provide fundamental new insights to strongly correlated quantum systems, molecular interactions and chemistry in the quantum regime, and precision measurement.  Complete control of molecular interactions by producing a molecular gas at very low entropy and near absolute zero has long been hindered by their complex energy level structure. Recently, a range of scientific tools have been developed to enable the production of molecules in the quantum regime. Here, molecular collisions follow full quantum descriptions.  Chemical reaction is controlled via quantum statistics of the molecules, along with dipolar effects. Further, molecules can be confined in reduced spatial dimensions and their interactions precisely manipulated via external electromagnetic fields.  For example, by encoding a spin-1/2 system in rotational states, we realize a spin lattice system where many-body spin dynamics are directly controlled by long-range and anisotropic dipolar interactions. These new capabilities promise further explorations of strongly interacting and collective quantum effects in exotic quantum matter.

SLIDESHOW:
ics Colloquium
Friday, April 17, 2015
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Wednesday, April 15, 2015
3:30 PM
Physics Building, Room 204
Boris Shklovskii [Host: E. Kolomeisky]
University of Minnesota
ics Special Colloquium: Hoxton Lecture


Wednesday, April 15, 2015
7:00 PM
Chemistry Building, Room Chemistry Building, Room 402
Alan Guth [Host: Brad Cox]
MIT
"Inflationary Cosmology: Is Our Universe Part of a Multiverse?"
 
 Slideshow (PDF)
ABSTRACT:

Inflationary cosmology gives a plausible explanation for many observed features of the universe, including its uniformity, its mass density, and the patterns of the ripples that are observed in the cosmic microwave background. Beyond what we can observe, most versions of inflation imply that our universe is not unique, but is part of a possibly infinite multiverse. I will describe the workings of inflation, the evidence for inflation, and why I believe that the possibility of a multiverse should be taken seriously.

SLIDESHOW:
ics Colloquium
Friday, April 10, 2015
3:30 PM
Physics Building, Room 204
ChanMo Park [Host: Seunghun Lee]
Chancellor of PUST/Former President of POSTECH
"Engaging with DPRK for Science Diplomacy and World Peace"
ABSTRACT:

As Chancellor of the Pyongyang University of Science & Technology (PUST) starting in October, 2010, I have seen the slow changes in DPRK, especially after Kim Jong Un took over the power in January, 2012. Globalizing DPRK is essential for peaceful coexistence and eventual reunification of two Koreas. One way to achieve this goal is Science Diplomacy, in particular educating young talents and globalizing them.

In this colloquium, a brief introduction about collaborative activities in science and technology between South and North Koreas will be presented, followed by more extensive presentation about the history and current status of PUST. And then the globalization efforts of PUST will be presented, to show that the PUST students are being internationalized and it is hoped that they will globalize their country in the near future, which will make an important contribution to the World Peace.

ics Colloquium
Friday, April 3, 2015
3:30 PM
Physics Building, Room 204
Mike Mulhearn [Host: Bob Hirosky]
UC Davis
"Discovering Ultra-High Energy Cosmic Rays with your Smartphone"
ABSTRACT:

Cosmic rays which encounter the Earth's atmosphere produce showers of muons and high-energy photons, which can be detected using a smartphone camera. The CRAYFIS experiment was devised to observe cosmic rays at ultra-high energy (UHE) using the existing network of smartphones as a ground detector array. We'll describe our custom app, our lab measurements of smartphone efficiency, and our latest projections for the sensitivity of the CRAYFIS array to UHE cosmic rays.

ics Colloquium
Friday, March 27, 2015
3:30 PM
Physics Building, Room 204
Gordon Cates [Host: Dinko Pocanic]
University of Virginia
"A new way to image: MRI with a 10,000,000-fold increase in sensitivity"
ics Colloquium
Friday, March 20, 2015
3:30 PM
Physics Building, Room 204
Peter Littlewood [Host: Despina Louca]
Argonne National Laboratory and University of Chicago
"Screening of charge and structural motifs in oxides"
ABSTRACT:

The boundary between metal and insulator remains a fruitful source of emergent phenomena in materials, ranging from oxides, to cold atoms. Typically the insulating side of this boundary is occupied by an electronic crystal (though often disordered), and at higher temperatures a polaronic liquid or bad metal. While the paradigm Hamiltonian for this transition involves only short –range electronic correlations, in practice the transition is tuned by disorder, by screening of longer range Coulomb forces, and by coupling to the lattice.  These lectures will discuss a few of these phenomena in real oxide systems including bulk and interface transition metal oxides.

Heterostructure oxides offer the opportunity to build in electric fields by precise control of chemistry on the atomic scale, used recently to generate modulation doping of two- dimensional electron gases (2DEG) in oxides. The origin of the 2DEG, whether in pristine or defected materials, is under debate. I will discuss the role of surface redox reactions, in particular O vacancies, as the source of mobile carriers, and also discuss their role in the switching of ferroelectricity in ultra-thin films.

While electric charges can be screened by mobile carriers, the same is not true of strain fields, which have intrinsic long-range interactions that cannot be screened. When strain fields are produced as a secondary order parameter in phase transitions - as for example in ferroelectrics - this produces unexpected consequences for the dynamics of order parameter fluctuations, including the generation of a gap in what would otherwise have been expected to be Goldstone modes. In some cases, eg manganites and nickelates, other intra-cell modes can nonlinearly screen the order parameter, which produces a strong sensitivity of ordering to octahedral rotations, essentially a jamming transition. This is relevant for tuning entropic effects at phase transitions, perhaps to enhance electro-caloric effects.

ics Colloquium
Friday, March 6, 2015
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, February 27, 2015
3:30 PM
Physics Building, Room 204
Nathan Lundblad [Host: Cass Sackett]
Bates College
"Quantum-gas physics in orbit: prospects for microgravity Bose-Einstein condensates aboard NASA's Cold Atom Laboratory"
 
 Slideshow (PDF)
ABSTRACT:

Notions of geometry, topology, and dimensionality have directed the historical development of quantum-gas physics, as has a relentless search for longer-lived matter-wave coherence and lower absolute temperature. With a toolbox of forces for confinement, guiding, and excitation, physicists have used quantum gases to test fundamental ideas in quantum theory, statistical mechanics, and in recent years notions of strongly-correlated many-body physics from the condensed-matter world.  Some of this work has been hampered by terrestrial gravity; levitation schemes of varying degree of sophistication are available, as are atomic-fountain and drop-tower microgravity facilities, but the long-term free-fall environment of low-Earth orbit remains a tantalizing location for quantum-gas experiments.

I will review a planned NASA microgravity program set to launch to the International Space Station in 2016. One set of experiments will explore a trapping geometry for quantum gases that is both theoretically compelling and difficult to attain terrestrially: that of a spherical or ellipsoidal shell. This trap could confine a Bose-Einstein condensate to the surface of an experimentally-controlled “bubble.” Other experiments will focus on atom interferometry and few-body physics. I will also review recent terrestrial work tailoring periodic geometries for BEC toward interesting solid-state analogues.

SLIDESHOW:
ics Colloquium
Thursday, February 26, 2015
3:30 PM
Physics Building, Room 204
Available
ics  Special Colloquium


Wednesday, February 25, 2015
3:30 PM
Physics Building, Room 204
Stephan Rachel [Host: Joe Poon]
Dresden University of Technology
"From correlated topological insulators to iridates and spin liquids"
ABSTRACT:

The non-interacting topological insulators (TIs) have attracted great interest in the last decade. While this class of materials is today well-understood, the effect of electron-eletron interactions in such systems remains in general elusive. In this talk, I will address two different aspects of interactions in 2D topological band structures: (i) in some cases, strongly interacting TI models can be used to describe the exotic magnetic properties of certain transition metal oxides. (ii) in other cases, strong interactions can drive a TI into spin-liquid phases.

ics Colloquium
Friday, February 20, 2015
3:30 PM
Physics Building, Room 204
Qaisar Shafi [Host: PQ Hung]
Bartol Institute, University of Delaware
"Inflation, Dark Matter, and Gravity Waves"
 
 Slideshow (PDF)
ABSTRACT:

The Standard Model of strong and electroweak interactions, together with Einstein's theory of general relativity, provide the basis for the highly successful hot big bang cosmology. A large quantity of groundbreaking cosmological observations favor an epoch of primordial inflation, during which the very early universe experienced an exponentially rapid expansion phase before transitioning to a hot, radiation dominated ('big bang') phase. The present universe, it is now widely accepted, is largely dominated by dark energy, whose nature is entirely mysterious, and also by dark matter, presumably consisting of some relic and still undetected elementary particle.

Some aspects of inflationary cosmology will be reviewed, including its prediction concerning the existence of primordial gravity waves whose discovery would have profound implications for high energy physics and cosmology.

SLIDESHOW:
ics  Special Colloquium


Thursday, February 19, 2015
3:30 PM
Physics Building, Room 204
Miles Stoudenmire [Host: Joe Poon]
Perimeter Institute
"Uncovering the Fibonacci Phase in Z3 Parafermion Systems"
 
 Slideshow (PDF)
ABSTRACT:

Recently there has been great progress in realizing platforms for topological quantum computation, with mounting evidence of the experimental observation of Majorana zero modes. However, braiding such zero modes does not yield a set of transformations sufficient to perform universal, fault tolerant computation. One way forward is to engineer systems realizing Z3 parafermion zero modes, which generalize Majorana zero modes. Coupled Z3 parafermions could hybridize into a phase supporting bulk Fibonacci anyons, a type of non-Abelian anyon that does have universal braiding statistics. 

Using the density matrix renormalization group (DMRG), we study a two-dimensional model of coupled Z3 parafermions. By working close to the weakly-coupled chain limit, we are able to identify the Fibonacci phase on cylinders as small as four sites in circumference then track its evolution, finding it survives even to the isotropic limit of our model on larger cylinders. We examine the extent of this phase and the wider phase diagram of our model, which turns out to harbor a second topological phase.

SLIDESHOW:
ics Colloquium
Friday, February 13, 2015
3:30 PM
Physics Building, Room 204
Andrei Malashevich [Host: Joe Poon]
Yale University
"First-principles studies of oxide surfaces and interfaces"
ABSTRACT:

Quantum-mechanical calculations based on methods that do not require any empirical input (first-principles calculations) have become an indispensable tool in studies of materials properties. In this talk, I will focus on applications of first-principles methods to studies of perovskite oxide surfaces and interfaces. Depending on the choice of cations, oxides can have almost any desired property. I will present two examples of materials that exhibit relation between structure and electronic properties at surfaces and interfaces. First, I will discuss an interface between metallic LaNiO3 thin film and ferroelectric PbTiO3. The polar field created by a ferroelectric can be used to modulate the conductivity of a channel material. This allows one to design non-volatile electronic devices based on the ferroelectric field effect. Typically, in the ferroelectric field effect, switching the polar state of a ferroelectric changes the carrier density in the channel material. I will show that in the LaNiO3/PbTiO3 interface the conductivity of the interface changes due to changes in carrier mobility, which in turn is related to structural distortions at the interface and appearance of two-dimensional conductivity in PbTiO3 at the interface. Second, I will present a study of properties of the (001) surfaces of thin LaNiO3 films. These films show dramatic differences in conductivity depending on the surface termination (LaO vs NiO2). We find that in this case, the conductivity is related to the polar structural distortions appearing at the surfaces of films.

ics  Special Colloquium


Monday, February 9, 2015
3:30 PM
Physics Building, Room 204
Utpal Chatterjee [Host: Joe Poon]
University of Virginia
"Phase incoherence driven melting of order parameters in cuprate high temperature superconductors and disordered charge density wave systems"
ABSTRACT:

Charge density waves (CDWs) and superconductivity are canonical examples of symmetry breaking in materials. Both are characterized by a complex order parameter – namely an amplitude and a phase. In the limit of weak coupling and in the absence of disorder, the formation of pairs (electron-electron for superconductivity, electron-hole for CDWs) and the establishment of macroscopic phase coherence both occur at the transition temperature Tc that marks the onset of long-range order. But, the situation may be different at strong coupling or in the presence of disorder. We have performed extensive experimental investigations on pristine and intercalated samples of 2H-NbSe2, a CDW material with strong electron-phonon coupling, using a combination of structural (X-ray), spectroscopic (photoemission and tunnelling) and transport probes. We find that Tc(δ) is suppressed as a function of the concentration (δ) of the intercalated atoms and eventually vanishes at a critical value of δ=δc leading to quantum phase transition (QPT). Our integrated approach provides clear signatures that the phase of the order parameter becomes incoherent at the quantum/ thermal phase transition, although the amplitude remains finite over an extensive region above Tc and beyond δc. This leads to the persistence of an energy gap in the electronic spectra even though there is no long-range order, a phenomenon strikingly similar to the so-called pseudogap in completely different systems such as high temperature superconductors, disordered superconducting thin films and cold atoms.

ics Colloquium
Friday, February 6, 2015
3:30 PM
Physics Building, Room 204
Gia-Wei Chern [Host: Joe Poon]
Los Alamos National Lab
"Stiffness from disorder in frustrated quasi-two-dimensional magnets"
ABSTRACT:

Frustrated magnetism has become an extremely active field of research. The concept of geometrical frustration dates back to Wannier’s 1950 study of Ising antiferromagnet on the triangular lattice. This simple system illustrates many defining characteristics of a highly frustrated magnet, including a macroscopic ground-state degeneracy and the appearance of power-law correlations without criticality. In this talk I will discuss a simple generalization of the triangular Ising model, namely, a finite number of vertically stacked triangular layers. Our extensive numerical simulations reveal a low temperature reentrance of two Berezinskii-Kosterlitz-Thouless transitions. In particular, I will discuss how short-distance spin-spin correlations can be enhanced by thermal fluctuations, a phenomenon we termed stiffness from disorder. This is a generalization of the well-known order-by-disorder mechanism in frustrated magnets. I will also present an effective field theory that quantitatively describes the low-temperature physics of the multilayer triangular Ising antiferromagnet.

ics Colloquium
Friday, January 30, 2015
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Thursday, January 29, 2015
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, January 23, 2015
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, January 16, 2015
3:30 PM
Physics Building, Room 204
Andrea Liu [Host: Seunghun Lee & Israel Klich]
University of Pennsylvania
"Jamming and the Anticrystal"
 
 Slideshow (PDF)
ABSTRACT:

When we first learn the physics of solids, we are taught the theory of perfect crystals. Only later do we learn that in the real world, all solids are imperfect. The perfect crystal is invaluable because we can describe real solids by perturbing around this extreme limit by adding defects. But such an approach fails to describe a glass, another ubiquitous form of rigid matter. I will argue that the jammed solid is an extreme limit that is the anticrystal--an opposite pole to perfect order. Like the perfect crystal, it is an abstraction that can be understood in depth and used as a starting point for understanding the mechanical properties of solids with surprisingly high amounts of order. Unlike the crystal, it is also a starting point for developing mechanical metamaterials whose Poisson ratios can be tuned anywhere from the completely incompressible to the completely auxetic limit.

SLIDESHOW:
ics Colloquium
Friday, December 5, 2014
3:30 PM
Physics Building, Room 204
Vidya Madhavan [Host: Jeffrey Teo]
University of Illinois at Urbana-Champaign
"Massless and Massive Electrons: Relativistic Physics in Condensed Matter Systems"
 
 Slideshow (PDF)
ABSTRACT:

Electrons in free space have a well-defined mass. Recently, a new class of materials called topological insulators were discovered, where the low energy electrons have zero mass. In fact, these electrons can be described by the same massless Dirac equation that is used to describe relativistic particles travelling close to the speed of light. In this talk I will describe our recent experimental and theoretical investigations of a class of materials called Topological Crystalline Insulators (TCIs) [1]. TCIs are recently discovered materials [2,3] where topology and crystal symmetry intertwine to create linearly dispersing Fermions similar to graphene. To study this material we used a scanning tunneling microscope [3,4,5]. With the help of our high-resolution data, I will show how zero-mass electrons and massive electrons can coexist in the same material. I will discuss the conditions to obtain these zero mass electrons as well the method to impart a controllable mass to the particles and show how our studies create a path to engineering the Dirac band gap and realizing interaction-driven topological quantum phenomena in TCIs.

 

[1] L. Fu, Topological Crystalline Insulators. Phys. Rev. Lett. 106, 106802 (2011).

[2] T. H. Hsieh et al., Topological crystalline insulators in the SnTe material class. Nat.Commun. 3, 982 (2012).

[3] Y. Okada, et al., Observation of Dirac node formation and mass acquisition in a topological crystalline insulator, Science 341, 1496-1499 (2013)

[4] Ilija Zeljkovic, et al., Mapping the unconventional orbital texture in topological crystalline insulators, Nature Physics 10, 572–577 (2014)

[5] Ilija Zeljkovic, et al., Dirac mass generation from crystal symmetry breaking on the surfaces of topological crystalline insulators, arXiv:1403.4906

SLIDESHOW:
ics Colloquium
Friday, November 21, 2014
3:30 PM
Physics Building, Room 204
David Alan Tennant [Host: Seunghun Lee]
Spallation Neutron Source, Oak Ridge National Laboratory
"Twists in quantum magnets"
 
 Slideshow (PDF)
ABSTRACT:

Neutrons provide the ability to look at quantum states of matter in unrivaled detail. Using quantum magnets in conjunction with magnetic fields exotic phases of matter can be generated that are highly quantum entangled. The wave functions in these states can be probed in space and time and in quantum critical states in particular elaborate symmetries and strange properties like fractional quantum numbers are revealed. In this talk I will show some of the remarkable physics that can be explored and how neutron scattering can be used to investigate what is going on.

SLIDESHOW:
ics Colloquium
Friday, November 14, 2014
3:30 PM
Physics Building, Room 204
CANCELED Peter Littlewood [Host: Despina Louca]
Argonne National Laboratory
"Screening of charge and structural motifs in oxides"
ABSTRACT:

The boundary between metal and insulator remains a fruitful source of emergent phenomena in materials, ranging from oxides, to cold atoms. Typically the insulating side of this boundary is occupied by an electronic crystal (though often disordered), and at higher temperatures a polaronic liquid or bad metal. While the paradigm Hamiltonian for this transition involves only short –range electronic correlations, in practice the transition is tuned by disorder, by screening of longer range Coulomb forces, and by coupling to the lattice.  These lectures will discuss a few of these phenomena in real oxide systems including bulk and interface transition metal oxides.

Heterostructure oxides offer the opportunity to build in electric fields by precise control of chemistry on the atomic scale, used recently to generate modulation doping of two- dimensional electron gases (2DEG) in oxides. The origin of the 2DEG, whether in pristine or defected materials, is under debate. I will discuss the role of surface redox reactions, in particular O vacancies, as the source of mobile carriers, and also discuss their role in the switching of ferroelectricity in ultra-thin films.

While electric charges can be screened by mobile carriers, the same is not true of strain fields, which have intrinsic long-range interactions that cannot be screened. When strain fields are produced as a secondary order parameter in phase transitions - as for example in ferroelectrics - this produces unexpected consequences for the dynamics of order parameter fluctuations, including the generation of a gap in what would otherwise have been expected to be Goldstone modes. In some cases, eg manganites and nickelates, other intra-cell modes can nonlinearly screen the order parameter, which produces a strong sensitivity of ordering to octahedral rotations, essentially a jamming transition. This is relevant for tuning entropic effects at phase transitions, perhaps to enhance electro-caloric effects.

ics Colloquium
Friday, November 7, 2014
3:30 PM
Physics Building, Room 204
Yuval Grossman [Host: Bob Hirosky]
Cornell University
"Leptogenesis"
 
 Slideshow (PDF)
ABSTRACT:

There are three open questions in physics which seem unrelated: Why is there only matter around us? How neutrinos acquire their tiny masses? Why all the particles in Nature have integer electric charge? It turns out that these open questions may be related. In this talk I will explain the questions, the connection between them and describe the on-going theoretical and experimental efforts in understanding them.

SLIDESHOW:
ics Colloquium
Friday, October 31, 2014
3:30 PM
Physics Building, Room 204
Ricardo Decca [Host: Genya Kolomeisky & Israel Klich]
IUPUI
"Hoping to get something out of nothing: Vacuum fluctuations and Newtonian (?) gravity"
ABSTRACT:

This talk deals with measurements of small forces at sub-micron separations. It tries to address an innocent enough question: Is Newtonian gravity valid at all distances? I will try to convey the deep sense of ignorance we still have in this topic, and describe the efforts undertaken to advance our knowledge. In particular, our experiments are sensitive to Yukawa-like corrections (i.e. interactions mediated by massive bosons) in the 0.1 to 1 micron range. 

It will be shown that when trying to measure the gravitational interaction at short separations (on the order of 100 nm), other forces have to be taken into account. Among them, vacuum fluctuations are the more ubiquitous ones.

A brief description of how macroscopic bodies (classical objects) interact with vacuum fluctuations (a purely quantum effect) will be presented… towards developing approaches that are insensitive to them! These approaches use an  engineered sample which allows to establish better constraints in Yukawa-like interactions. This is accomplished by measuring the difference in forces in configurations where vacuum fluctuations are the same, but the corrections to Newtonian gravity (if any) are not.

ics Colloquium
Friday, October 24, 2014
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, October 17, 2014
3:30 PM
Physics Building, Room 204
Genya Kolomeisky [Host: Dinko Pocanic]
University of Virginia
"Fermion space charge in narrow-band gap semiconductors, Weyl semimetals and around highly charged nuclei"
 
 Slideshow (PDF)
ABSTRACT:

The field of charged impurities in narrow-band gap semiconductors and Weyl semimetals can create electron-hole pairs when the total charge $Ze$ of the impurity exceeds a value $Z_{c}e.$ The particles of one charge escape to infinity, leaving a screening space charge. The result is that the observable dimensionless impurity charge $Q_{\infty}$ is less than $Z$ but greater than $Z_{c}$. There is a corresponding effect for nuclei with $Z >Z_{c} \approx 170$, however in the condensed matter setting we find $Z_{c} \simeq 10$. Thomas-Fermi theory indicates that $Q_{\infty} = 0$ for the Weyl semimetal, but we argue that this is a defect of the theory. For the case of a highly-charged recombination center in a narrow band-gap semiconductor (or of a supercharged nucleus), the observable charge takes on a nearly universal value. In Weyl semimetals the observable charge takes on the universal value $Q_{\infty} = Z_{c}$ set by the reciprocal of material's fine structure constant.

SLIDESHOW:
ics Colloquium
Friday, October 10, 2014
3:30 PM
Physics Building, Room 204
Richard Stone [Host: Seunghun Lee]
American Association for the Advancement of Science
"The Sacred Volcano, and other true stories from North Korea"
ics Colloquium
Friday, October 3, 2014
3:30 PM
Physics Building, Room 204
William Wester [Host: Craig Group]
Fermilab
"Non-WIMPy Dark Matter Searches at Fermilab"
 
 Slideshow (PDF)
ABSTRACT:

With the observation of the Higgs Boson in July 2012, high energy physics has claimed victory in accounting for all the known particles within the Standard Model of Particle Physics. However, great and profound questions remain unanswered regarding the nature of energy, matter, space and time. Among these questions is "What is the nature of Dark Matter" that accounts for approximately 80% of the matter in the universe. Gaining popularity is to invoke the possibility that "Non-WIMPy" new particles form the dark matter in contrast to usual Weakly Interacting Massive Particles hypothesis. Novel ideas and novel experiments, often at a very small scale, are exploring large areas of previously unexplored parameter space. Plus, they are a lot of fun too!

SLIDESHOW:
ics Colloquium
Friday, September 26, 2014
3:30 PM
Physics Building, Room 204
Scott Walker [Host: Joe Poon]
Hughes Aircraft and GM Hughes Electronics
"AS I REMEMBER. A Walk Through My Years at Hughes Aircraft"
 
 Slideshow (PDF)
ABSTRACT:

The basic theme of the talk is to emphasize the value of a physics degree when dealing with a wide spectrum of technical products and systems. Following the story line of his career as presented in his recent autobiography “As I Remember”, Scott will discuss the development of a number of military systems, US and international. In a light handed manner, he will summarize some community projects such as the Discovery Science Center in southern California, funding of a tax initiative for improved local transportation, and the formation by local businesses of the Robert Saunders scholarship for the school of engineering at UC Irvine. He will relate his physics background to the development of new semiconductor components and advanced automotive electronics, including the development of the EV-1, the first US commercial all electric vehicle by GM.

Bio: Dr. Walker received his Ph.D. in nuclear physics from the University of Virginia in 1961. Moving to California upon graduation, he joined Hughes Aircraft Company later to become GM Hughes Electronics. Over the next 37 years at Hughes he was given increasingly wide management responsibilities for the design and production of military systems, advanced industrial electronic components, international programs for air traffic control systems, both military and commercial, and advanced automotive electronics. Retiring in 1997 as Corporate Senior Vice President and member of the Office of the Chairman, Scott and his wife of fifty six years now reside in Indianapolis, Indiana.

SLIDESHOW:
ics Colloquium
Friday, September 19, 2014
3:30 PM
Physics Building, Room 203
Ralph Allen [Host: Rick Marshall]
University of Virginia, Environmental Health & Safety
"Hoo's going to help me? START to help you keep the evidence"
 
 Slideshow (PDF)
ABSTRACT:

Accidents in academic research labs around the country have called attention to the lack of attention to safety when researchers assume that students understand the risks in their labs. Many of the hazardous materials have become increasingly regulated and granting agencies are now demanding evidence that environmental and safety regulations are followed. The first thing that regulators review are training records. The Office of Environmental Health and Safety has developed a program to help researchers document training and assist in improving laboratory safety.

SLIDESHOW:
ics Colloquium
Friday, September 12, 2014
3:30 PM
Physics Building, Room 204
Alex Retzker [Host: Israel Klich]
The Hebrew University of Jerusalem
"Quantum microscopy with NV centers in diamonds"
 
 Slideshow (PDF)
ABSTRACT:

In recent years there has been a growing effort to develop a new type of microscopy, which is based on the NV (Nitrogen Vacancy) centers in diamonds. In this colloquium I will overview the latest results in this field and present a few quantum enhanced measurement schemes to image single protons using NV centers in diamond. These schemes will use ideas from quantum coherent control and quantum computing and will mainly target imaging with biological goals.

SLIDESHOW:
ics Colloquium
Friday, September 5, 2014
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, August 29, 2014
3:30 PM
Physics Building, Room 204
Sidney Nagel [Host: Seunghun Lee]
University of Chicago
"The Life and Death of a Drop: Transitions and Singularities"
ABSTRACT:

The exhilarating spray from waves crashing onto the shore, the distressing sound of a faucet leaking in the night, and the indispensable role of bubbles dissolving gas into the oceans are but a few examples of the ubiquitous presence and profound importance of drop formation and splashing in our lives. They are also examples of a liquid changing its topology as it breaks into pieces. Although part of our common everyday experience, these changes are far from understood and reveal profound surprises upon careful investigation. For example, in droplet fission the fluid forms a neck that becomes vanishingly thin at the point of breakup so that there is a dynamic singularity in which physical properties such as pressure diverge. Singularities of this sort often organize the overall dynamical evolution of nonlinear systems. In this lecture, I will give the life history of a drop – from its birth to its eventual demise – illustrating the passage of its existence with the scientific surprises that determine its fate.

ics Colloquium
Friday, April 25, 2014
3:30 PM
Physics Building, Room 204
Seth Putterman [Host: Israel Klich]
UCLA
"Unknowns of energy concentrating phenomena"
ABSTRACT:
The path to equilibrium is not controlled by entropy production. Although entropy increases with every time step, dynamical motion can be dominated by nonlinear physical processes that spontaneously concentrate energy density. In sonoluminescence a bubble concentrates the energy of a traveling sound wave by 12 orders of magnitude to create picoseconds flashes of blackbody radiation that originate in a new state of matter. When surfaces are brought into and out of contact they exchange charge: a process called tribo-electrification. This phenomenon can be so strong that the power applied to peel sticky tape is efficiently transduced into a flux of high energy electrons, and x-ray photons that can expose an image in a few seconds. For a ferroelectric crystal, instabilities in the phonon spectrum lead to a spontaneous polarization that for Lithium Niobate reaches 15.million volts per cm. The temperature dependence of this field can be used to build a neutron generator based on the fusion of deuterium nuclei. These phenomena challenge a reductionist approach to the theoretical physics of emergent phenomena. The degree to which the energy density of a continuous system can be concentrated by off-equilibrium motion has not been determined by theory. For sonoluminescence, we do not know if the parameter space includes a region where an extra factor of 100 in energy density makes it possible to realize thermonuclear fusion. For triboelectrification, we do not have an ab-initio theory of charge transfer. And for ferroelectrics we do not have an ab-initio theory of the limits of spontaneous polarization which can be designed.
ics INPP Second Annual Lecture
Friday, April 18, 2014
3:30 PM
Physics Building, Room 203
Gordon Kane [Host: Dinko Pocanic]
University of Michigan
"String Theory, Our Real World, and Higgs bosons"
 
 Slideshow (PDF)
ABSTRACT:
String theory is exciting because it can address most or all of the questions we hope to understand about the physical world, about the quarks and leptons that make up our world, and the forces that act on quarks and electrons to form our world, cosmology, and much more. It’s nice that it provides a quantum theory of gravity too. I’ll explain why string theory is testable in basically the same ways as the rest of physics, why many people including string theorists are confused about that, and how string theory is already or soon being tested in several ways, including Higgs boson physics and LHC physics.
SLIDESHOW:
ics Colloquium
Friday, April 11, 2014
3:30 PM
Physics Building, Room 204
Subir Sachdev [Host: Seunghun Lee]
Harvard University
"Unveiling the order of the high temperature superconductors"
ABSTRACT:
A central mystery posed by the Cu-based high temperature superconductors has been the nature of their electronic state at low hole density. I will survey the remarkable progress made by recent experiments towards solving this mystery. The experiments show that there is a density-wave order with d symmetry. This is distinct from the d symmetry of the wavefunction of the Cooper pairs responsible for the superconductivity. I will review theories which anticipated these developments.
ics Colloquium: Optical Society of America, UVA Student Chapter
Friday, April 4, 2014
3:30 PM
Physics Building, Room 204
Barry Sanders [Host: Niranjan Sridhar]
University of Calgary
"Whither Quantum Computing?"
 
 Slideshow (PDF)
ABSTRACT:
A working quantum computer would be revolutionary because certain problems, such as simulating quantum materials or factorization, are easily solved on a quantum computer and probably forever hard on non-quantum computers no matter how small or how fast. Quantum computing technology is at an early stage so we do not yet know which medium is best. I discuss the principles of quantum computing, technological efforts for its realization (embellished with animated films), and applications for when a quantum computer eventually works.
SLIDESHOW:
ics Hoxton Lecture


Thursday, March 27, 2014
7:00 PM
Chemistry 402, Room 402
H. Jeff Kimble [Host: Brad Cox]
Caltech
"Quantum Networks in Quantum Optics"
ABSTRACT:

This talk will discuss the opportunities for the exploration of physical systems that have not heretofore existed in the natural world.

ics Colloquium
Friday, February 21, 2014
3:30 PM
Physics Building, Room 204
Pei Wang [Host: Olivier Pfister]
University of Virginia
"Quantum computing with hypercubes of light"
 
 Slideshow (PDF)
ABSTRACT:
Quantum computing promises exponential speedup for particular computational tasks, such as factoring integers[1] and quantum simulation[2]. There are two main flavors of quantum computing: the circuit model and the measurement-based model---in particular, one-way quantum computing [3], which is implemented by applying measurements on an entangled resource known as a cluster state. Complicated computation tasks require the scalable generation of cluster states, which remains a formidable challenge. Pfisterlabs at UVa has been working on generating scalable cluster states and has successfully built some interesting cluster states [4,5].

In this colloquium, I will first explain continuous variable one-way quantum computing, cluster states, and then present our new proposal of a simple, "top-down" setup to generate large-size, D-hypercubic-lattice CV cluster states of more than 6000 entangled modes using D identical optical parametric oscillators (OPOs), each with a two-frequency pump [6]. These cluster states are sufficient for universal one-way quantum computation [3], and the high dimensional lattices are useful in quantum error correction based on Kitaev's surface code [7]. Our optical construction methods eschews the limitations of a three-dimensional world, enabling simulation of measurements on these high-valence cluster graphs and also inviting theoretical and experimental investigations of their topological properties [8].

References:
1. P.W.Shor, in Proceedings, 35th Annual Symposium on Foundations of Computer Science, edited by S.Goldwasser(IEEE press, Los Alamitos, CA, Santa Fe, NM,1994) pp. 124-134.
2. R.P.Feynman, Int.J.Theor.Phys.21,467 (1982)
3. R.Raussendorf and H.J.Briegel, "A one-way quantum computer", Phys.Rev.Lett. 86,5188(2001)
4. M.Pysher et al., "Parallel generation of quadripartite cluster entanglement in the optical frequency comb", Phys.Rev.Lett. 107, 030505(2011)
5. M.Chen, N.C.Menicucci,and O.Pfister,"Experimental realization of multipartite entanglement of 60 modes of the quantum optical frequency comb", arXiv:1311.2957[quant-ph](2013)
6. P.Wang, M.Chen, N.C.Menicucci,and O.Pfister,"Weaving quantum optical frequency combs into hypercubic cluster states", arXiv:1309.4105[quant-ph] (2013)
7. R.Raussendorf, J.Harrington, and K.Goyal,"A fault-tolerant one-way quantum computer", Ann. Phys.(N.Y.) 321, 2242–2270 (2006)
8. T. F. Demarie, T. Linjordet, N. C. Menicucci, and G. K. Brennen, Detecting Topological Entanglement Entropy in a Lattice of Quantum Harmonic Oscillators, arXiv:1305.0409 [quant-ph] (2013)

SLIDESHOW:
ics INPP Second Annual Lecture
Friday, February 14, 2014
3:30 PM
Physics Building, Room 203
Gordon Kane [Host: Dinko Pocanic]
University of Michigan
"String Theory, Our Real World, and Higgs bosons"
ABSTRACT:
String theory is exciting because it can address most or all of the questions we hope to understand about the physical world, about the quarks and leptons that make up our world, and the forces that act on quarks and electrons to form our world, cosmology, and much more. It’s nice that it provides a quantum theory of gravity too. I’ll explain why string theory is testable in basically the same ways as the rest of physics, why many people including string theorists are confused about that, and how string theory is already or soon being tested in several ways, including Higgs boson physics and LHC physics.
ics Colloquium
Friday, January 31, 2014
3:30 PM
Physics Building, Room 204
Pradeep Kumar [Host: Bellave Shivaram]
University of Florida
"Universality in the Magnetic Response of Metamagnetic Materials"
ics Colloquium
Friday, December 6, 2013
3:30 PM
Physics Building, Room 204
Marija Vucelja [Host: Joe Poon]
Rockefeller University
"Non-equilibrium statistical physics, population genetics and evolution"
 
 Slideshow (PDF)
ABSTRACT:
I will present a glimpse into the fascinating world of biological complexity from the perspective of theoretical physics. Currently the fields of evolution and population genetics are undergoing a renaissance, with the abundance of accessible sequencing data. In many cases the existing theories are unable to explain the experimental findings. The least understood aspects of evolution are intrinsically quantitative and statistical and we are missing a suitable theoretical description. It is not clear what sets the time scales of evolution, whether for antibiotic resistance, emergence of new animal species, or the diversification of life. I will try to convey that physicists are invaluable in framing such pertinent questions. The emerging picture of genetic evolution is that of a strongly interacting stochastic system with large numbers of components far from equilibrium. In this colloquium I plan to focus on the dynamics of evolution. I will discuss evolutionary dynamics on several levels. First on the microscopic level - an evolving population over its history explores a small part of the whole genomics sequence space. Next I will coarse-grain and review evolutionary dynamics on the phenotype level. I will also discuss the importance of spatial structures and temporal fluctuations. Along the way I will point out similarities with physical phenomena in condensed matter physics, polymer physics, spin-glasses and turbulence.
SLIDESHOW:
ics Colloquium
Friday, November 22, 2013
3:30 PM
Physics Building, Room 204
Bob McKeown [Host: Nilanga Liyanage & Gordon Cates]
Jefferson Lab
"Neutrinos: Masters of Surprise"
 
 Slideshow (PDF)
ABSTRACT:
In the recent past the experimental study of neutrinos has yielded a series of surprising results. The very light masses and strong flavor mixing have challenged theorists and also motivated experimentalists to perform ever more sensitive experiments. In this colloquium I will discuss these developments, including the observation of the unexpectedly large mixing angle θ13 by the Daya Bay reactor neutrino experiment. Prospects for future studies, and opportunities for additional surprises, will also be discussed.
SLIDESHOW:
ics Colloquium
Friday, November 15, 2013
3:30 PM
Physics Building, Room 204
Eun-Suk Seo [Host: Craig Group]
University of Maryland
"Recent Discoveries of Cosmic Ray Anomalies"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Friday, October 25, 2013
3:30 PM
Physics Building, Room 204
Jason Alicea [Host: Paul Fendley]
Caltech
"Majorana Materializes"
 
 Slideshow (PDF)
ABSTRACT:
The 1937 theoretical discovery of Majorana fermions (particles that are their own anti-particles) has since impacted diverse problems ranging from neutrino physics and dark matter searches to the quantum Hall effect and superconductivity. This talk will survey recent revolutionary advances in the condensed matter pursuit of these elusive objects. In particular, I will discuss new ways of "engineering" Majorana platforms using exceedingly simple building blocks, along with pioneering experiments that have made impressive progress towards realizing Majorana fermions. These developments mark the first steps of a fascinating research program that could eventually overcome one of the grand challenges in the field—the synthesis of a scalable quantum computer.
SLIDESHOW:
ics Colloquium
Friday, October 4, 2013
3:30 PM
Physics Building, Room 204
Nadia Fomin [Host: Dinko Pocanic]
University of Tennessee, Knoxville
"Particle and Nuclear physics with cold neutrons"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Friday, September 27, 2013
3:30 PM
Physics Building, Room 204
Bruce Patton [Host: Joe Poon]
The Ohio State University
"Experiences with a "Jackson by Inquiry" electromagnetism course and the connection with neural networks, recent cognitive neuroscience, and modern theories of teaching/learning"
ABSTRACT:
The electromagnetism course is often a singular experience in the education of a physics student, graduate and undergraduate. We described recent experiments to deliver the highly technical material in the electromagnetism course in an active learning studio lab format that current physics education research suggests is more optimal. Exploration of the results leads to connections with neuronal network models of the brain, modern neurophysiology and cognitive science, a simple phenomenological model of the teaching/learning process, and optimal design of the learning environment.
ics Colloquium
Friday, September 20, 2013
3:30 PM
Physics Building, Room 204
Chris Neu [Host: Joe Poon]
University of Virginia
"The Interplay Between the Top Quark and the Higgs Boson: How a discovery from a generation ago can help us understand the latest breakthrough in particle physics"
 
 Slideshow (PDF)
ABSTRACT:
The recent discovery at the LHC of a new fundamental particle has generated a significant amount of excitement around the globe -- an excitement unmatched in particle physics since the discovery of the top quark in 1995. Given its observed decay channels, its mass and a handful of its properties, indications are that this new particle could be the long-sought Higgs boson, the particle which is purported to be the linchpin in understanding the imposition of mass to the fundamental particles. However much remains to be known -- it could be the Higgs boson predicted by the standard model or it could be something more exotic. Complete characterization of this new particle must be done in order to understand its true nature; its interactions with the top quark will play a vital role in this endeavor. Herein I describe the importance the top quark will play in studies of this new particle, and describe in detail one particularly important channel in the characterization effort: the search for production of the Higgs boson in association with top-quark pairs at CMS.
SLIDESHOW:
ics Colloquium
Friday, September 6, 2013
3:30 PM
Physics Building, Room 204
Graduate Townhall Meeting
ics Colloquium
Friday, August 30, 2013
3:30 PM
Physics Building, Room 204
Israel Klich & Seunghun Lee [Host: Joe Poon]
University of Virginia
"When a theorist met an experimentalist or vice versa"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Friday, April 26, 2013
4:00 PM
Physics Building, Room 204
Philip Kim [Host: Seunghun Lee]
Columbia University
"Bloch, Landau, and Dirac: Hofstadter's Butterfly in Graphene"
 
 Slideshow (PDF)
ABSTRACT:
Electrons moving in a periodic electric potential form Bloch energy bands where the mass of electrons are effectively changed. In a strong magnetic field, the cyclotron orbits of free electrons are quantized and Landau levels forms with a massive degeneracy within. In 1976, Hofstadter showed that for 2-dimensional electronic system, the intriguing interplay between these two quantization effects can lead into a self-similar fractal set of energy spectrum known as "Hofstadter's Butterfly." Experimental efforts to demonstrate this fascinating electron energy spectrum have continued ever since. Recent advent of graphene, where its Bloch electrons can be described by Dirac fermions, provides a new opportunity to investigate this half century old problem experimentally. In this presentation, I will discuss the experimental realization Hofstadter's Butterfly via substrate engineered graphene under extremely high magnetic fields controlling two competing length scales governing Dirac-Bloch states and Landau orbits, respectively.
SLIDESHOW:
ics Hoxton Lecture


Thursday, April 18, 2013
7:00 PM
Chemistry Building, Room Chemistry 402
Chris Quigg [Host: Brad Cox]
Fermi National Accelerator Laboratory
"The World According to Higgs"
ABSTRACT:

New developments in particle physics offer a new and radically simple conception of the universe. Fundamental particles called quarks and leptons make up everyday matter, and two new laws of nature rule their interactions. Until July 4, 2012, our neat story was missing one piece, a particle called the Higgs boson. Without it, there would be no atoms, no chemistry, no liquids or solids, and no basis for life. Why did thousands of physicists devote decades to the hunt, and how does the “discovery of the century” change the way we see the world?

ics Joint Chemistry & Physics Colloquium
Friday, April 12, 2013
4:00 PM
Physics Building, Room 203
Eric Mazur [Host: Kevin Lehmann & Brad Cox]
Harvard University
"Nonlinear optics at the nanoscale Physics"
ics Colloquium
Friday, April 5, 2013
4:00 PM
Physics Building, Room 204
Christopher White [Host: Craig Dukes]
Illinois Institute of Technology
"Current Results in Neutrino Physics"
ABSTRACT:
Despite decades of research, neutrinos are still one of the least understood fundamental particles. Despite a world-wide experimental effort over the past 20 years that has started to reveal the neutrino's secrets, there is much more to be learned. One of the hopes is that a detailed study of neutrino properties will help us understand the observed asymmetry between matter and antimatter in the universe. It is also becoming clear that neutrinos play a key role in a variety of astrophysical phenomena, such as supernova explosions. I will review what is currently known about neutrinos as well as near and longer term experimental efforts.
ics Colloquium
Friday, March 29, 2013
4:00 PM
Physics Building, Room 204
Thia Keppel [Host: Nilanga Liyanage]
Jefferson Lab
"Medical applications of nuclear physics"
ics Colloquium
Friday, March 1, 2013
4:00 PM
Physics Building, Room 204
Ehud Altman [Host: Israel Klich]
Weizmann Institute
"Emergent phenomena and universality in quantum systems far from thermal equilibrium"
 
 Slideshow (PDF)
ABSTRACT:
Recent experiments with ultra-cold atomic gases and trapped ions as well as solid-state devices such as superconducting circuits designed to manipulate q-bits, are posing a new challenge for theory. As in traditional atomic physics these systems are often prepared far from equilibrium, or continuously driven by electromagnetic fields. At the same time they retain a many-body character and intricate quantum correlations, which define a new class of quantum matter. I will first review recent experimental advances in this field and then address a theoretical question: Can the complexity of quantum dynamics in these systems give rise to robust universal phenomena in spite of the non-equilibrium conditions?
SLIDESHOW:
ics Joint Colloquium: Physics Department & Society of Physics Students
Friday, February 22, 2013
4:00 PM
Physics Building, Room 203
Richard Berg [Host: Craig Group]
University of Maryland
"The Physics IQ Test"
 
 Slideshow (PDF)
ABSTRACT:
The assembled throngs vote on the outcome of counterintuitive "brainteaser" type physics questions, which are then answered by performing simple physics demonstration experiments. One interesting result is that the average score is about the same for groups ranging from high school students to physics professors.
SLIDESHOW:
ics Colloquium
Friday, February 1, 2013
4:00 PM
Physics Building, Room 204
Mark Alford [Host: Diana Vaman]
Washington University in St. Louis
"Superconducting Quarks: Condensed Matter in the Heavens"
 
 Slideshow (PDF)
ABSTRACT:
In this talk I will describe the densest predicted state of matter—color-superconducting quark matter. A color superconductor is very different from an "ordinary" electrical superconductor: it occurs at ultra-high density and has a much richer phase structure because quarks come in many varieties. This form of matter may well exist in the core of neutron stars, and the search for signatures of its presence is currently proceeding. I will give an accessible review of the features of color-superconducting quark matter, and discuss some ideas for finding it in nature.
SLIDESHOW:
ics Colloquium
Friday, January 18, 2013
4:00 PM
Physics Building, Room 204
Eugene Demler [Host: Israel Klich]
Harvard University
"Exploring topological states with cold atoms and photons"
ABSTRACT:
I will review recent theoretical ideas and experimental realizations of topological states using ultracold atoms in optical lattices and quantum walk protocols with photons. Such systems enabled several types of measurements, which had not been possible in solid state systems, including direct measurements of the Berry/Zak phases of Bloch bands and observation of edge states on domain walls in the one dimensional SSH model. I will also discuss new types of topological states in periodically modulated Floquet-Bloch bands which have been realized in photon quantum walks.
ics Colloquium
Friday, December 7, 2012
4:00 PM
Physics Building, Room 204
John Arrington [Host: Donal Day]
Argonne National Laboratory
"Clusters, Correlations, and Quarks: A High-Energy Perspective on Nuclei"
 
 Slideshow (PDF)
ABSTRACT:
While nuclei form the core of matter, an understanding of their structure in terms of their fundamental constituents, quarks and gluons, is still well out of reach due to the complex nature of quark interactions in Quantum chromodynamics (QCD). Therefore, "effective" models of nuclei are needed as input for different measurements, from the simple collection of quasifree quarks used in high energy scattering measurements to complex shell structure studied in low energy nuclear physics. These models are useful because of the large separation between the natural energy and distance scales associated with QCD, nuclear binding, and atomic physics. However, there are regions where interactions at vastly different scales have non-trivial interactions which can be seen in high-precision measurements or for specific, well-chosen observables. I will provide some examples of this mixing of energy scales and then focus on the overlap between the scales relevant for nuclear structure and those probed in medium- and high-energy studies of nucleon structure. High-density configurations and large virtual excitations in nuclei provide increased interplay between nuclear scales and QCD, providing opportunities for higher energy measurements to probe details of nuclear structure, and yielding phenomena where low energy nuclear structure may impact the quark description of matter.
SLIDESHOW:
ics Colloquium
Friday, November 30, 2012
4:00 PM
Physics Building, Room 204
Alec Habig [Host: Craig Dukes]
University of Minnesota Duluth
"The Supernova Early Warning System (SNEWS)"
 
 Slideshow (PDF)
ABSTRACT:
SNEWS is a cooperative effort between the world's neutrino detection experiments to spread the news that a star in our galaxy has just experienced a core-collapse event and is about to become a Type II Supernova. This project exploits the ~hours time difference between neutrinos promptly escaping the nascent supernova and photons which originate when the shock wave breaks through the stellar photosphere, to give the world a chance to get ready to observe such an exciting event at the earliest possible time. A coincidence trigger between experiments is used to eliminate potential local false alarms, allowing a rapid, automated alert. A new experiment which will participate in SNEWS is the Helium and Lead Observatory. HALO is a new, dedicated supernova neutrino experiment being built in SNOLAB from a combination of lead and the SNO experiment's old He3 neutron counters. It is designed to be a low-maintenance, high-livetime, and long-lived experiment to complement existing, multi-purpose neutrino detectors.
SLIDESHOW:
ics Colloquium
Friday, November 16, 2012
4:00 PM
Physics Building, Room 204
Gene Mele [Host: Genya Kolomeisky]
University of Pennsylvania
"Topological Band Theory and Twisted Multilayer Graphene"
 
 Slideshow (PDF)
ABSTRACT:
Topological insulators are a recently discovered quantum electronic phase of matter. This talk will give a brief overview of the known electronic phases of matter, focusing on the unique properties of topological insulators and their discovery from a careful consideration of the low energy electronic physics of single-layer graphene. Closely related topological ideas are then used to analyze the mysterious electronic behavior of a family of multilayer graphenes known as “twisted” graphenes in which a rotation of neighboring layers leads to unexpectedly rich low energy physics.
SLIDESHOW:
ics Colloquium: Optical Society of America, UVA Student Chapter
Friday, November 9, 2012
4:00 PM
Physics Building, Room 204
Margaret Murnane [Host: Reihaneh Shahrokhshahi]
University of Colorado at Boulder
"Bright Coherent Ultrafast X-Ray Beams on a Tabletop and Applications in Nano and Materials Science"
 
 Slideshow (PDF)
ABSTRACT:
Ever since the invention of the laser 50 years ago, scientists have been striving to extend coherent laser-like beams into the x-ray region of the spectrum. Very recently, the prospects for tabletop x-ray beams at wavelengths <10Å have brightened considerably. This advance is the direct result of a new ability to manipulate electrons on their natural, attosecond (10^-18s), time-scales using femtosecond lasers. In recent work we uncovered a new regime of nonlinear optics, where bright laser-like X-ray supercontinua with photon energies >1.6keV (wavelengths < 8Å) can be produced from a tabletop femtosecond laser [1]. This represents the most extreme >5001 order nonlinear optical process known. X-rays are powerful probes of the nanoworld. They penetrate thick samples and can image small objects. This talk will also highlight how ultrafast x-rays can capture the coupled motions of charges, spins, phonons and photons that underlie function on the fastest timescales. [2,3]
1. Popmintchev et al, Science 336, 1287 (2012).
2. Mathias, et al, PNAS 109, 4792 (2012).
3. Rudolf et al., Nature Commun 3, 1037 (2012).
SLIDESHOW:
ics Colloquium
Friday, October 12, 2012
4:00 PM
Physics Building, Room 204
Diana Vaman [Host: Joe Poon]
University of Virginia
"Holograms of strings"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Friday, October 5, 2012
4:00 PM
Physics Building, Room 204
Nilanga Liyanage [Host: Joe Poon]
University of Virginia
"Precision studies of the nucleon"
ics Colloquium
Friday, September 28, 2012
4:00 PM
Physics Building, Room 204
Stefan Baessler [Host: Joe Poon]
University of Virginia
"Fundamental physics with free neutrons"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Friday, September 21, 2012
4:00 PM
Physics Building, Room 204
Israel Klich [Host: Joe Poon]
University of Virginia
"Quantum fluctuations: From the Casimir Effect to Quantum Entanglement"
ABSTRACT:
In the world of quantum mechanics, nothing is certain, including the meaning of "nothing". Indeed, the Casimir effect, an attraction between two mirrors separated by vacuum, sometimes called “A force from nothing”, is an example of the intricate consequences of taking quantum mechanics seriously. The Casimir effect has been in the spotlight in the last decade, as its importance beyond fundamental physics and its experimental demonstration have been realized. The effect is gaining relevance in areas as diverse as cosmology, quantum field theory, condensed matter physics, biology and nanotechnology. In this talk, I will explore the role of quantum fluctuations, and radiation matter coupling in creating this force, as well as present new results on another aspect of quantum fluctuations of great importance: that of entanglement. In particular, I will explore the entanglement between radiation and matter in a framework inspired by the Casimir effect.
ics Colloquium
Friday, September 14, 2012
4:00 PM
Physics Building, Room 204
Craig Group [Host: Joe Poon]
University of Virginia
"Higgs Boson Searches at the CDF Experiment: Highlights of UVa Contributions to a Successful Search with the Full Data Set"
 
 Slideshow (PDF)
ABSTRACT:
I present the results from the CDF experiment on the direct searches for a Standard Model Higgs boson produced in p-pbar collisions at a center of mass energy of 1.96 TeV, using the data corresponding to integrated luminosity of up to 10fb-1. The searches are performed in the Higgs boson mass range from 100 to 200 GeV/c2. The dominant decay channels, H → bb and H → W W , are combined with all the secondary channels and significant analysis improvements have been recentlyimplemented to maximize the search sensitivity. UVa contributions to these analyses, their recent improvements, and to the leadership of the effort are highlighted. The results from the CDF experiment are combined with the D0 experiment, both using their full data sets, and a significant excess of data events compared to background prediction is reported. The highest local significance is 3.0 standard deviations while global significance for such an excess anywhere in the full mass range investigated is approximately 2.5 standard deviations. Both experiments at the Large Hadron Collider have recently reported excesses of greater than 5standard deviations in their searches for the Higgs boson. The complementarity and relevance of the Tevatron results are discussed in the context of this recent discovery from the LHC.
SLIDESHOW:
ics Colloquium
Friday, September 7, 2012
4:00 PM
Physics Building, Room 204
Ralph Allen [Host: Rick Marshall]
University of Virginia
"Devoting your life to scientific research does not mean that you should actually risk your life and granting as well as regulatory agencies will make sure that you don't"
ABSTRACT:
Accidents in academic research labs around the country have called attention to the lack of attention to safety when researchers assume that students understand the risks in their labs. Many of the hazardous materials have become increasingly regulated and granting agencies are now demanding evidence that environmental and safety regulations are followed. The first thing that regulators review are training records. The Office of Environmental Health and Safety has developed a program to help researchers document training and assist in improving laboratory safety.
ics Colloquium
Friday, August 31, 2012
4:00 PM
Physics Building, Room 204
Enrico Rossi [Host: Genya Kolomeisky]
College of William & Mary
"Graphene: how electrons move and interact in the ultimate flatland"
ABSTRACT:
Graphene is a one atom-thick layer of carbon atoms arranged in a two-dimensional honeycomb lattice that was first realized in a laboratory in 2004. In graphene the electrons are strictly con fined to live in two dimensions and behave as massless Dirac fermions described by two-dimensional Quantum Electro Dynamics (QED), albeit with a much lower (1/300 th) speed of light and bigger (≈ 1), and tunable, fine structure constant. Due to its unique electronic structure graphene exhibits anomalous electronic properties. In this talk I will discuss the unusual transport properties of graphene and provide a theoretical explanation of the "puzzles" posed by graphene transport measurements since its discovery. I will then discuss the eff ect of electron-electron interactions. Most of the experiments suggest that in single layer graphene the interactions have only a quantitative eff ect. However, recently very high quality graphene heterostructures have been realized and the experimental measurements conducted on them suggest that in these structures the interactions can drive the electrons into novel spontaneously broken symmetry ground states. I will present our theoretical study of "hybrid" heterostructures formed by one sheet of single layer graphene and one sheet of bilayer graphene and show that in these structures the spontaneously broken symmetry ground state is 2-fold degenerate with one of the degenerate states analogous to a superfluid chiral state. The chiral nature of one of the degenerate ground states opens the possibility to observe in graphene heterostructures topologically protected midgap states analogous to Majorana modes.
ics Colloquium
Friday, April 27, 2012
4:00 PM
Physics Building, Room 204
Bellave Shivaram [Host: Brad Cox]
University of Virginia
"101 Years of Superconductivity - My Contributions Therein"
ABSTRACT:
Starting from a brief history of its initial discovery I will trace the development/study of various classes of superconducting materials. I will cover the phenomenology in these different classes with references to microscopic theory where appropriate, and also present a concurrent description of my own experimental contributions.
ics Special Colloquium: Hoxton Lecture


Thursday, April 12, 2012
7:00 PM
Chemistry Building, Room 402
Edward Moses [Host: Brad Cox]
National Ignition Facility
"The National Ignition Facility: Pathway to Energy Security and Physics of the Cosmos"
ABSTRACT:

The National Ignition Facility (NIF), at Lawrence Livermore National Laboratory in Livermore, California, is the world’s most energetic laser system. NIF is capable of producing over 1.8 MJ and 500 TW of ultraviolet light, 100 times more than any other operating laser. Completed in March 2009, it is maturing rapidly and transitioning into the world’s premier high-energy-density science experimental facility, while supporting its strategic security, fundamental science, and energy security missions.

By concentrating intense laser energy into target only millimeters in length, NIF can, for the first time, produce conditions emulating those found in planetary interiors and stellar environments and creating fusion energy to power our future. The extreme conditions of energy density, pressure, and temperature will enable scientists to pursue fundamental science experiments designed to address a range of scientific questions, from observing new states of matter to exploring the origin of ultrahigh-energy cosmic rays. Early experiments have been successfully completed in support of materials equations of state, materials strength, and radiation transport in extreme temperature and pressure conditions.

The National Ignition Campaign, an international effort pursued on the NIF, aims to demonstrate fusion burn and generate more energy output than the laser energy delivered to the target. Achieving this ignition goal will validate the viability of inertial fusion energy (IFE) as a clean source of energy. A laser-based IFE power plant will require advances in high-repetition-rate lasers, large-scale target fabrication, target injection and tracking, and other supporting technologies. These capabilities could lead to an operational prototype IFE power plant in 10 to 15 years. LLNL, in partnership with academia, national laboratories, and industry, is developing a Laser Inertial Fusion Energy (LIFE) baseline design concept and examining technology choices for developing a LIFE prototype power plant.

This talk will describe the unprecedented experimental capabilities of the NIF, its role in strategic security and fundamental science, and the pathway to achieving fusion ignition to create a clean and secure energy future.

ics Colloquium
Friday, April 6, 2012
4:00 PM
Physics Building, Room 204
Bernd Surrow [Host: Nilanga Liyanage]
Temple University
"Fundamental measurements of the proton's sub-structure using high-energy polarized proton-proton collisions "
 
 Slideshow (PDF)
ABSTRACT:
Understanding the structure of matter in terms of its underlying constituents has a long tradition in science. A key question is how we can understand the properties of the proton, such as its mass, charge, and spin (intrinsic angular momentum) in terms of its underlying constituents: nearly massless quarks (building blocks) and massless gluons (force carriers). The strong force that confines quarks inside the proton leads to the creation of abundant gluons and quark-antiquark pairs (QCD sea). These ‘silent partners’ make the dominant contribution to the mass of the proton. Various polarized deep-inelastic scattering measurements have shown that the spins of all quarks and antiquarks combined account for only 25% of the proton spin. New experimental techniques are required to deepen our understanding on the role of gluons and the QCD sea to the proton spin. High energy polarized proton-proton (p + p) collisions at RHIC at Brookhaven National Laboratory provide a new and unique way to probe the proton spin structure using very well established processes in high-energy physics, both experimentally and theoretically. A major new tool has been established for the first time using parity-violating W boson production in polarized p + p collisions at s = 500 GeV demonstrating directly the different polarization patterns of different quark flavors, paving the path to study the polarization of the QCD sea. Various results in polarized p + p collisions at s = 200 GeV constrain the degree to which gluons are polarized suggesting that the contribution of the gluons to the spin of the proton is rather small, in striking contrast to their role in making up the mass of the proton.
SLIDESHOW:
ics Colloquium
Friday, March 23, 2012
4:00 PM
Physics Building, Room 203
Sir David King [Host: John T. Yates, Jr., Ian Harrison, & Brad Cox]
Smith School at Oxford
"A Scientific Analysis of 21st Century Environmental and Economic Challenges"
ABSTRACT:
Unprecedented improvements in human wellbeing over the nineteenth and twentieth centuries have been driven largely by developments flowing from advances in engineering, medicine, agriculture and technology, and by political and economic developments coupled to consumerism. But a necessary consequence of these successes has been an equally unprecedented growth in the global population. The twenty first century will be dominated by the challenges posed by a mid-century population of around 9 billion people, all seeking a high standard of living. Ecosystem services, an essential element of our continued wellbeing as a species, are already under threat as our need for food production, fresh water, energy sources, minerals etc. grows exponentially to meet unfettered demand. Climate change, driven by fossil fuel usage and by deforestation, provides the biggest challenge of all, since it requires a collective response of the global population, to mitigate the effect and to manage the growing impacts upon our societies.

Well designed technological solutions are desirable and can be compatible with the continued growth of human wellbeing. The socio-political challenges in directing such a collective response are beyond anything previously managed. This may well lead to a mid-century slide into conflict caused by environmental and resource-driven challenges on a scale not previously experienced. The thesis presented here is that meeting these challenges will require a global cultural and technological transformation on much the same scale as the European Renaissance or the Industrial Revolution itself, and a clear understanding by all societies of the need to adapt and strengthen global governance procedures. Decision making at all levels will require significantly enhanced knowledge and understanding.

ics Special Colloquium: Institute of Nuclear and Particle Physics Annual Lecture
Thursday, March 15, 2012
3:30 PM
Physics Building, Room 203
Bill Marciano [Host: INPP]
Brookhaven National Laboratory
"Tales from the Darkside of Particle Physics"
 
 Slideshow (PDF)
ABSTRACT:
The "Minimal" Standard Model of particle physics is almost complete. Interesting hints of a standard Higgs Boson are starting to appear at CERN and one can ask, Is it all that remains to be discovered? Dark matter observations suggest that an invisible universe of massive particles may exist all around us, but coupled to normal matter primarily by gravity. Can we detect dark particles and study their properties at accelerators? In this talk, I will discuss the implications of a Higgs Boson discovery and speculate on its possible connection to "dark" matter physics. In particular, properties of the "dark" photon, a hypothetical "dark" force carrier, along with ongoing and proposed experimental efforts to discover, it will be described.
SLIDESHOW:
ics Colloquium
Friday, March 2, 2012
4:00 PM
Physics Building, Room 204
Sama Bilbao Y Leon [Host: Simonetta Liuti]
Virginia Commonwealth University
"The Next Generation of Nuclear Reactor Designs"
 
 Slideshow (PDF)
ABSTRACT:
There are today over 440 commercial nuclear power reactors operating in 30 countries. They provide about 14% of the world's electricity in the form of economic, environmentally sound and reliable base-load power. In addition, 63 new nuclear reactors are currently under construction in 14 countries. But much has changed in the design of nuclear reactors since the first commercial nuclear power stations started operating in the 1950s. Modern nuclear reactors, those that will be built in the short term, achieve improvements over existing designs through small to moderate modifications, with a strong emphasis on maintaining design provenness and building upon the lessons learnt from 40 years of successful operation, to minimize technological and investment risks. At the same time, nuclear designers are already working on a new generation of nuclear reactor concepts incorporating radical conceptual changes in design approaches or system configuration in comparison with existing practice. Substantial research and development efforts, feasibility tests, as well as a prototype or demonstration plant are probably required prior to the commercial deployment of these innovative designs. This talk will provide an overview of the most recent developments in nuclear reactor design, including those using alternative fuel cycles, such as Thorium.
SLIDESHOW:
ics Special Colloquium
Thursday, February 23, 2012
3:30 PM
Physics Building, Room 204
Xiang Cheng [Host: Seunghun Lee]
Cornell University
"Imaging the microscopic structure of shear thinning and thickening colloidal suspensions"
ABSTRACT:
While a simple Newtonian fluid such as water flows with a constant viscosity, many structured fluids ranging from polymer melts to surfactant solutions exhibit fascinating non-Newtonian flow behaviors including shear thinning and shear thickening. One typical example is a colloidal suspension, where its viscosity can vary by orders of magnitude depending on how quickly it is sheared. Although these non-Newtonian behaviors are believed to arise from the arrangement of suspended particles and their mutual interactions, microscopic particle dynamics in such suspensions are difficult to measure directly. Here, by combining fast confocal microscopy with simultaneous force measurements, we systematically investigate a suspension's structure as it transitions through regimes of different flow signatures. Our measurements of the microscopic single-particle dynamics unambiguously show that shear thinning results from the decreased relative contribution of entropic forces and that shear thickening arises from particle clustering induced by inter-particle hydrodynamic lubrication forces. Furthermore, we explore out-of-equilibrium structures of sheared colloidal suspensions and report a novel string phase, where particles link into log-rolling strings normal to the plane of shear. Our techniques illustrate an approach that complements current methods for determining the microscopic origins of non-Newtonian flow behavior in complex fluids.
ics Special Colloquium
Monday, February 20, 2012
3:30 PM
Physics Building, Room 204
Haidong Zhou [Host: Seunghun Lee]
National High Magnetic Field Lab
"Spin Ice and Quantum Spin Liquid in Geometrically Frustrated Magnets"
 
 Slideshow (PDF)
ABSTRACT:
In geometrically frustrated magnets (GFMs), the incompatibility between the interactions of the magnetic degrees of freedom in a lattice and the underling crystal geometry leads to the frustration. The massive level of degeneracy introduced by this frustration can persist to low temperatures to enhance the spin fluctuations and suppress the magnetic ordering, therefore resulting exotic spin ground states with abnormal thermo-dynamics. In this talk, two GFMs will be introduced: (i) Spin ice with pyrochlore structure, in which the ground state is a short range ordering of the “two spin in two spin out” configurations on tetrahedrons following the “ice rule”; (ii) Quantum spin liquid (QSL), in which the strong quantum fluctuations of the spins with small number (S = 1/2 and 1) destroy the magnetic ordering and lead to a spin-liquid like ground state. Following the introduction, we present our recently studies on new pyrochlore materials Pr2Sn2O7 and Dy2Ge2O7, and new QSL materials Ba3CuSb2O9 and Ba3NiSb2O9 with a triangular lattice of S = 1/2 and S = 1, respectively.
SLIDESHOW:
ics Special Colloquium
Thursday, February 16, 2012
3:30 PM
Physics Building, Room 204
Cheng Cen [Host: Seunghun Lee]
IBM
"Oxide Nanoelectronics on Demand"
ABSTRACT:
Complex oxides and their heterostructures have exhibited a great collection of novel functionalities and are considered one of the most promising candidate for next generation technological materials. At the interface formed between LaAlO3 and SrTiO3, by scanning a biased conducting atomic force microscope (AFM) tip along a programmed trajectory at room temperature, we can reversibly control in nanoscale the metal-insulator transition. With this technique, a variety of rewritable nanoscale devices and structures have been studied. These nanostructures, which are mainly assembled from basic elements including conductive wires and dots with characteristic dimensions just a few nanometers, show great performance as field effect transistors, nanodiodes and photodetectors. At low temperatures, a variety of electronic, spintronic and superconducting properties are observed, with enormous potential for exploitation in quantum devices.
ics Special Colloquium
Monday, February 13, 2012
3:30 PM
Physics Building, Room 204
Sami Amasha [Host: Seunghun Lee]
Stanford University
"Pseudo-spin Resolved Transport Spectroscopy of the Kondo Effect"
ABSTRACT:
In strongly-correlated materials, such as high-temperature superconductors and heavy fermion compounds, electrons form many-body states with properties different from those of non-interacting electrons. A simpler and better understood example of electron correlations is the Kondo effect, which describes how spins of conduction electrons screen the spin of a localized electron that has degenerate spin states (spin-up and spin-down in the case of a localized spin-1/2 electron). This screening generates spin correlations. Electrical transport measurements of a single quantum dot can probe Kondo physics; however, to directly access the spin correlations one needs spin-resolved measurements. We address this challenge by using the orbital states of a double quantum dot as pseudo-spin states: an electron on the left/right dot is associated with pseudo-spin up/down. When the energies of these pseudo-spin states are degenerate, Kondo screening occurs. We establish a correspondence between spin Kondo in a single dot and pseudo-spin Kondo in double dots. We use this to show that our pseudo-spin resolved spectroscopy measurements of the Kondo state in a double dot correspond to predictions for spin-resolved spectroscopy of spin Kondo. Finally, we explore the interplay between orbital and spin degeneracy in this double dot system.
ics Colloquium
Friday, February 10, 2012
4:00 PM
Physics Building, Room 204
Robert W. Michaels [Host: Xiaochao Zheng]
Thomas Jefferson National Accelerator Facility
"The Lead Radius Experiment PREX"
 
 Slideshow (PDF)
ABSTRACT:
The Lead Radius Experiment PREX ran in the Spring of 2010 in Hall A at the Thomas Jefferson National Accelerator Facility (JLab). The experiment measures the parity-violating asymmetry in the elastic scattering of longitudinally polarized electrons from a 208Pb nucleus at an energy of 1.06 GeV and a scattering angle of 5. The Z boson that mediates the weak neutral interaction couples mainly to neutrons and provides a clean, model-independent measurement of the RMS radius Rn of the neutron distribution in the nucleus. This measurement is a fundamental test of nuclear structure theory, and our result establishes the existence of the neutron skin, i.e. that Rn > Rp. A precise measurement of Rn pins down the density-dependence of the symmetry energy of neutronrich nuclear matter, which has impacts on neutron star structure, heavy ion collisions, and atomic parity violation experiments. The experiment involves all aspects of the JLab accelerator, from the polarized source to the detector, and capitalizes on JLab’s unique strengths for carrying out high-precision parity experiments. In addition to the 2010 data, several technical challenges will be described, as well as prospects for future measurements at JLab from 208Pb and other nuclei such as 48Ca.
SLIDESHOW:
ics Special Colloquium
Thursday, February 9, 2012
3:30 PM
Physics Building, Room 204
Kenjiro Gomes [Host: Seunghun Lee]
Stanford University
"Tailoring Dirac Fermions in Molecular Graphene"
ABSTRACT:
The dynamics of electrons in solids is tied to the band structure created by a periodic atomic potential. The design of artificial lattices, assembled through atomic manipulation, opens the door to engineer electronic band structure and to create novel quantum states. We present scanning tunneling spectroscopic measurements of a nanoassembled honeycomb lattice displaying a Dirac fermion band structure. The artificial lattice is created by atomic manipulation of single CO molecules with the scanning tunneling microscope on the surface of Cu(111). The periodic potential generated by the assembled CO molecules reshapes the band structure of the two-dimensional electron gas, present as a surface state of Cu(111), into a "molecular graphene" system. We characterize the band structure through Fourier transform analysis of impurity scattering maps. We tailor this new tunable class of graphene to reveal signature topological properties: an emergent mass and energy gap created by breaking the pseudospin symmetry with a Kekule bond distortion; gauge fields generated by applying atomically engineered strains; and the condensation of electrons into quantum Hall-like states and topologically confined phases.
ics Colloquium
Friday, January 27, 2012
4:00 PM
Physics Building, Room 204
Lawrence Thomas [Host: Dinko Pocanic]
University of Virginia
"N-polaron systems and mathematics"
 
 Slideshow (PDF)
ABSTRACT:
The polaron is a mathematical model for a “dressed” particle consisting of an electron together with its entourage of local excitations of a quantized phonon field. We will give a brief historical review of the polaron, including the analysis of its ground state by a Brownian motion functional integral and by a related variational expression.
For the case of two or more electrons, the interaction of the electrons with the phonon field gives rise to an effective attraction between electrons that causes the particles to bind together. For N electrons, N → ∞, the systems are unstable in the sense that the binding energy grows faster than linearly in N. We will discuss recent work with Frank, Lieb, and Seiringer which shows that sufficiently strong Coulomb repulsion between electrons can compensate for this binding and provide stability for polaron systems for large N.
SLIDESHOW:
ics Special Colloquium
Thursday, January 26, 2012
3:30 PM
Physics Building, Room 204
Utpal Chatterjee [Host: Seunghun Lee]
Argonne National Laboratory
"Characterizing phase diagram of High Temperature Superconductors via Angle Resolved Photoemission Spectroscopy"
ABSTRACT:
High Temperature Superconductors (HTSCs) were discovered more than 25 years ago. However, a microscopic theory of them is yet to be realized. In order to identify the mechanism behind superconductivity in these systems, we must understand the normal state from which superconductivity emerges. From our detailed Angle Resolved Photoemission Spectroscopy (ARPES) measurements on Bi2Sr2CaCu2O8+δ (BISCO 2212) HTSCs we have found that unlike conventional superconductors, where there is a single temperature scale Tc separating the normal from the superconducting state, HTSCs are associated with two additional temperature scales. One is the so-called pseudogap scale T*, below which electronic states are partially gapped, while the second one is the coherence scale Tcoh, characterizing the onset of a significant enhancement in electronic lifetime. We have observed that both T* and Tcoh change strongly with carrier concentration and they cross each other near optimal doping, i.e. the carrier concentration at which an HTSC attains its maximum Tc. Furthermore, there is an unusual phase in the normal state where the electronic excitations are gapped as well as coherent. Quite remarkably, this is the phase from which the superconductivity with maximum Tc emerges. Our experimental finding that T* and Tcoh intersect is not compatible with the theories invoking “single quantum critical” point near optimal doping, rather it is more naturally consistent with the theories of superconductivity for doped Mott insulators.
ics Colloquium
Friday, January 20, 2012
4:00 PM
Physics Building, Room 204
Jerry Gilfoyle [Host: Simonetta Liuti]
University of Richmond
"Putting the Genie Back in the Bottle: The Science of Nuclear Non-Proliferation"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Friday, December 2, 2011
4:00 PM
Physics Building, Room 204
William Cooke [Host: Tom Gallagher]
College of William and Mary
"How Green Can Algae Be? Alternative Energy from the Chesapeake Algae Project"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Friday, November 18, 2011
4:00 PM
Physics Building, Room 204
Daniel Elvira [Host: Brad Cox]
Fermi National Accelerator Lab
"Searching for Supersymmetry at the LHC"
 
 Slideshow (PDF)
ABSTRACT:
Supersymmetry is a theory build under the hypothesis that there is a relation between bosons and fermions. The particle physics community finds it very compelling because it provides a solution to the mass hierarchy problem, allows a percent level unification of gauge couplings, and predicts a particle candidate for dark matter. The Large Hadron Collider (LHC) at CERN is the best instrument with count with at the moment to search for supersymmetric particles. It has delivered proton-proton collisions at a center of mass energy of 7 TeV since 2010. The CMS and ATLAS experiments at the LHC are expected to collect 4-5 fb-1 of data before the end of 2011 and explore a very significant fraction of the phase space associated with the most simple supersymmetric models. This talk will go over the experimental strategy for SUSY searches at the LHC, explain the techniques to evaluate the main backgrounds to potential SUSY signals, and review the most recent results.
SLIDESHOW:
ics Special Colloquium
Monday, November 14, 2011
3:30 PM
Physics Building, Room 204
Bob Hirosky [Host: Joe Poon]
University of Virginia
"Peering into dark corners at Fermilab and CERN"
ics Colloquium
Friday, November 11, 2011
4:00 PM
Physics Building, Room 204
Marianna Safronova [Host: Kent Paschke]
University of Delaware
"Atomic calculations for tests of fundamental physics"
 
 Slideshow (PDF)
ABSTRACT:
I will give an overview of applications of atomic calculations for atomic physics tests of fundamental physics, including the study of parity violation, search for EDM, and search for variation of fundamental constants. The goals of high-precision atomic parity violation (APV) studies are to search for new physics beyond the standard model of the electroweak interaction by accurate determination of the weak charge and to probe parity violation in the nucleus. I will discuss the current status and future prospects of atomic parity violation studies and the implications for searches for physics beyond the standard model. The recent advances in theoretical methodology that allowed to reduce theoretical uncertainty in the analysis of the cesium experiment are briefly outlined. I will also discuss recent accurate calculation of the nuclear spin-dependent parity-violating amplitude. New result still leads to the discrepancy between constraints on weak nucleon-nucleon coupling obtained from the cesium anapole moment and those obtained from other nuclear PV measurements.
SLIDESHOW:
ics Colloquium
Friday, November 4, 2011
4:00 PM
Physics Building, Room 204
Thomas Schaefer [Host: Peter Arnold]
North Carolina State University
"Nearly perfect fluidity: From cold atoms to hot quarks and gluons"
 
 Slideshow (PDF)
ABSTRACT:
A dimensionless measure of fluidity is the ratio of shear viscosity to entropy density. In this talk we will argue that fluidity is a sensitive probe of the strength of correlations in a fluid. We will also discuss evidence that the two most perfect fluids ever observed are also the coldest and the hottest fluid ever created in the laboratory. The two fluids are cold atomic gases (~10^(-6) K) that can be probed in optical traps, and the quark gluon plasma (~10^{12} K) created in heavy ion collisions at RHIC (Relativistic Heavy Ion Collider at Brookhaven National Laboratory). Remarkably, both fluids come close to a bound on the shear viscosity that was first proposed based on calculations in string theory, involving non-equilibrium evolution of back holes in 5 (and more) dimensions.
SLIDESHOW:
ics Special Colloquium
Thursday, November 3, 2011
3:30 PM
Physics Building, Room 204
Kent Paschke [Host: Joe Poon]
University of Virginia
"Electrons and Mirror Symmetry"
 
 Slideshow (PDF)
SLIDESHOW:
ics Special Colloquium
Monday, October 31, 2011
3:30 PM
Physics Building, Room 204
Xiaochao Zheng [Host: Joe Poon]
University of Virginia
"What Have We Learned from Electron Deep Inelastic Scattering?"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Friday, October 28, 2011
4:00 PM
Physics Building, Room 204
Di Xiao [Host: Joe Poon]
Oak Ridge National Lab
"Topological Insulators: From Fundamentals to Applications"
ABSTRACT:
Topological insulators are materials that have a bulk band gap like an ordinary insulator but support protected conducting states on their edge or surface. These edge/surface states are predicted to have special properties that could be useful for applications ranging from spintronics to quantum computing. In this talk, I will explain the nontrivial band topology of these materials using the Berry phase concept, review current progress on material prediction and realization, and discuss some of the applications in surface catalysis and electronics.
ics Special Colloquium
Thursday, October 27, 2011
4:00 PM
Physics Building, Room 204
Marvin Weinstein [Host: Simonetta Liuti]
Stanford University
"Diving For Treasure In Complex Data "
 
 Slideshow (PDF)
ABSTRACT:
All fields of scientific research have experienced an explosion of data. It is a formidable computational challenge to analyze this data to extract unexpected patterns. Meeting this challenge will require new, advanced methods of analysis. Dynamic Quantum Clustering is such a tool. The algorithm, invented by David Horn (Tel Aviv University) and myself, provides a highly visual and interactive tool that allows one to explore complicated data that has unknown structure. My talk will provide a brief introduction to the distinction between supervised and unsupervised methods in data mining (clustering in particular). Then, I will, very briefly, discuss the theory of DQC. The bulk of my talk will be devoted to showing results on a data set coming from the Stanford Synchrotron Radiation Laboratory and some results from data on earthquakes in the Middle East. These examples show the power of DQC applied to data sets on which the currently most favored unsupervised data mining techniques fail to obtain any interesting results. The message will be that large, complex, data sets typically exhibit extended structures that are significant and that cannot be seen by other methods.
SLIDESHOW:
ics Special Colloquium
Wednesday, October 26, 2011
3:30 PM
Physics Building, Room 204
Austen Lamacraft [Host: Joe Poon]
University of Virginia
"Statistical mechanics and dynamics of multicomponent quantum gases"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Friday, October 21, 2011
4:00 PM
Physics Building, Room 204
RESERVED
ics Colloquium
Friday, October 14, 2011
4:00 PM
Physics Building, Room 204
Francis Robicheaux [Host: Bob Jones]
Auburn University
"Antihydrogen Trapped"
 
 Slideshow (PDF)
ABSTRACT:
Atoms made of a particle and an antiparticle are unstable, usually surviving less than a microsecond. Antihydrogen, the bound state of an antiproton and a positron, is made entirely of antiparticles and is believed to be stable. It is this longevity that holds the promise of precision studies of matter-antimatter symmetry. Low energy (Kelvin scale) antihydrogen has been produced at CERN since 2002. I will describe the experiment which has recently succeeded in trapping antihydrogen in a cryogenic Penning trap for times up to approximately 15 minutes.
SLIDESHOW:
ics Colloquium: Kickoff Event for The Optical Society of America at UVA
Friday, October 7, 2011
4:00 PM
Physics Building, Room 204
Malvin Teich [Host: Lauren Levac]
Boston University
"Multi-Photon and Entangled-Photon Imaging and Lithography"
 
 Slideshow (PDF)
ABSTRACT:
Nonlinear optics, which governs the interaction of light with various media, offers a whole raft of useful applications in photonics, including multiphoton microscopy and multiphoton lithography. It also provides the physicist with a remarkable range of opportunities for generating light with interesting, novel, and potentially useful properties. As a particular example, entangled-photon beams generated via spontaneous optical parametric down-conversion exhibit unique quantum-correlation features and coherence properties that are of interest in a number of contexts, including imaging. Photons are emitted in pairs in an entangled quantum state, forming twin beams. Such light has found use, for example, in quantum optical coherence tomography, a quantum imaging technique that permits an object to be examined in section. Quantum entanglement endows this approach with a remarkable property: it is insensitive to the even-order dispersion inherent in the object, thereby increasing the resolution and section depth that can be attained. We discuss the advantages and disadvantages of a number of techniques in multiphoton and entangled-photon imaging and lithography.
SLIDESHOW:
ics Colloquium
Friday, September 30, 2011
4:00 PM
Physics Building, Room 204
Hugh Gusterson [Host: Seunghun Lee]
George Mason University
"The cultural and ethical world of nuclear weapons scientists"
 
 Slideshow (PDF)
ABSTRACT:
The Los Alamos and Lawrence Livermore National Laboratories are the two largest employers of physicists in the country. Their primary mission is nuclear weapons science. Based on over two decades studying the culture of nuclear weapons scientists as an anthropologist, the speaker discusses the values of nuclear weapons physicists, the reasons young physicists have for choosing a career in nuclear weapons design, the ethical challenges they confront, and the degree of job satisfaction they report.
SLIDESHOW:
ics Colloquium
Friday, September 23, 2011
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, September 16, 2011
4:00 PM
Physics Building, Room 204
John Delos [Host: Tom Gallagher]
College of William and Mary
"Electronic Detection and Diagnosis of Health and Illness of Premature Infants"
ABSTRACT:
The pacemaking system of the heart is complex; a healthy heart constantly integrates and responds to extracardiac signals, resulting in highly complex heart rate patterns with a great deal of variability. In the laboratory and in some pathological or age related states, however, dynamics can show reduced complexity that is more readily described and modeled. Reduced heart rate complexity has both clinical and dynamical significance - it may provide warning of impending illness or clues about the dynamics of the heart's pacemaking system. Here we describe simple and interesting heart rate dynamics that we have observed in premature human infants - reversible transitions to large- amplitude periodic oscillations - and we show that they give early warning of bacterial infections in premature infants, and we show that the appearance and disappearance of these periodic oscillations can be described by a simple mathematical model, a Hopf bifurcation.
ics Colloquium
Friday, September 9, 2011
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, September 2, 2011
4:00 PM
Physics Building, Room 204
Cheng Chin [Host: Seunghun Lee]
University of Chicago
"Having your cake and seeing it too: In Situ Observation of Incompressible Mott Domains in Ultracold Atomic Gases"
 
 Slideshow (PDF)
ABSTRACT:
Atoms at ultralow temperatures are fascinating quantum objects, which can tunnel through barriers, repel or attract each other, and interfere like electromagnetic waves. This wavy behavior of ultracold atoms evidently illustrates the particle-wave duality as discussed in modern physics. By loading repulsively interacting atoms into a regular array of tiny optical cells (called optical lattices), we show that the wavy nature of the atoms can be completely destroyed. At the same time, the gaseous sample develops an interesting multi-layer structure with quantize density plateaus, resembling a multi-tier wedding cake. Our observation of the cake structure in ultracold gases of atoms [1] raises new prospects to investigate the dynamics and transport across a phase boundary [2] and to identify universal critical behavior in the transition regime [3]. Surprising findings along these directions will be reported.
SLIDESHOW:
ics Colloquium
Friday, August 26, 2011
4:00 PM
Physics Building, Room 204
RESERVED
ics Colloquium
Friday, April 29, 2011
4:00 PM
Physics Building, Room 204
Stefan Bekiranov [Host: Eugene Kolomeisky]
UVA Medical School
"Application of Machine Learning Methods to Genome-Wide Maps of Histone Methylations"
 
 Slideshow (PDF)
ABSTRACT:
The physical length of one copy of the human genome is a little over 1 meter. It is packaged into a nucleus, which is on the order of micrometers in diameter. This is achieved by wrapping the DNA around histones. In the last decade, many breakthroughs have lead to the understanding that these histones control subsets of genes that are turned on or off depending on chemical modifications on their tails. They accomplish this by controlling the accessibility of proteins—responsible for turning genes on—to DNA. This accessibility can be characterized by two states: open and closed. Remarkably, over 60 different locations on these tails are subject to at least one of eight types of chemical modifications. Recently, it has been shown that many of these modifications work together to robustly turn genes on or off; however, we are at the beginning of uncovering this complex control network. To shed light on this network, we apply computational methods, which identify statistically significant combinations, to genome wide maps of histone modifications. We indeed find that crosstalk among these modifications is extensive and predict novel combinations, which strongly synergize in our models, for further biochemical study.
SLIDESHOW:
ics National Physics Day Show
Wednesday, April 27, 2011
7:00 PM
Physics Building, Room 203
A Family-Oriented Event
 
"Physics professors Bob Jones, Olivier Pfister, Cass Sackett, and Steve Thornton will delight the crowd with strange and mystifying events."
ABSTRACT:
See rockets shooting around the auditorium, balls suspended in air, curve balls flying overhead, Van de Graaff generators, skaters spinning around. You will see you a bunch of fascinating things you should never do at home. We might even put someone on a bed of nails and crush a cement block on top of them. As usual, there will be plenty of surprises in store. These demonstrations will intrigue and excite both young and old and from novice to expert. Bring your family and friends, but come on time. For more information about this free public event call 924-3781.
ics Colloquium
Friday, April 22, 2011
4:00 PM
Physics Building, Room 204
Sylvester J. Gates [Host: Diana Vaman]
University of Maryland
"The Quincunx Point"
ABSTRACT:
Sometimes theoretical physics problems resist resolution for decades. Endeavoring to solve such problems can lead to a new and unexpected viewpoint. Prof. Gates will describe such a problem and describe how trying to solve it has possibly led to a quincunx point at the five-fold overlap of art, mathematics, music, science, and perhaps...
ics Colloquium
Friday, April 15, 2011
4:00 PM
Physics Building, Room 204
Assa Auerbach [Host: Israel Klich]
Technion, Israel Institute of Technology
"Elementary Particles of Superconductivity"
 
 Slideshow (PDF)
ABSTRACT:
Historically, two paradigms competed to explain superconductivity (i) Bose Einstein Condensation of weakly interacting Charge 2e pairs (Schafroth), and (ii) Pairing instability of the Fermi liquid (BCS). BCS theory was the unquestionable winner until the late 80's. BCS approximations however, have suffered major setbacks in the advent of high temperature, short coherence length superconductors, such as cuprates, pnictides, and granular superconducting films. A third paradigm has offered itself: Hard Core lattice Bosons (HCB), which are experimentally realized in cold atoms on optical lattices. HCB behave less like weakly interacting bosons or fermions, but (strangely) more like quantum spins. Their static correlations are very well understood by theories of quantum antiferromagnets. Recent calculations of the conductivity of Hard Core Bosons suggests a new route to understanding linear in temperature resistivity and other strange metallic properties above the transition temperature.
SLIDESHOW:
ics Colloquium
Friday, April 8, 2011
4:00 PM
Physics Building, Room 204
RESERVED
ics Hoxton Lecture


Thursday, April 7, 2011
7:00 PM
Chemistry , Room 402
Burton Richter [Host: Brad Cox]
Stanford University
"Beyond Smoke and Mirrors: Climate Change and Energy in the 21st Century"
 
 Slideshow (PDF)
ABSTRACT:

Professor Richter is the co-winner of the 1976 Nobel Prize in physics for the discovery of the J/Ψ particle which was the first observation of a particle containing a fourth quark named the charm quark and was a central part of the so-called November revolution of particle physics. He has accumulated many other honors in his career including a long tenure as the director of Stanford Linear Acceleratory Laboratory from 1984 to 1999. He has also been the recipient of the E.O. Lawrence Medal, has served as president of the American Physical Society, and is a member of the National Academy of Sciences. He presently serves on the board of directors of Scientists and Engineers for America, an organization focused on promoting sound science in American government and is a Senior Fellow by Courtesy of the Center for Environmental Science and Policy at Stanford Institute for International Studies. In the past several years Professor Richter has turned his attention to the central problem of the 21st century, the effect of human activity on the global climate. He has written a book with the same title as his lecture.

SLIDESHOW:
ics Colloquium
Friday, April 1, 2011
4:00 PM
Physics Building, Room 204
Grad Poster Competition
ics Colloquium
Friday, March 25, 2011
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, March 18, 2011
4:00 PM
Physics Building, Room 204
Reserved
ics Colloquium
Friday, March 4, 2011
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, February 25, 2011
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, February 18, 2011
4:00 PM
Physics Building, Room 204
Peter Lu [Host: Peter Arnold]
Harvard University
"Modern math in medieval islamic architecture"
ABSTRACT:
The conventional view holds that girih (geometric star-and-polygon) patterns in medieval Islamic architecture were conceived by their designers as a network of zigzagging lines, and drafted directly with a straightedge and a compass. I will describe recent findings that, by 1200 C.E., a conceptual breakthrough occurred in which girih patterns were reconceived as tessellations of a special set of equilateral polygons (girih tiles) decorated with lines. These girih tiles enabled the creation of increasingly complex periodic girih patterns, and by the 15th century, the tessellation approach was combined with self-similar transformations to construct nearly-perfect quasicrystalline patterns. Quasicrystal patterns have remarkable properties: they do not repeat periodically, and have special symmetry---and were not understood in the West until the 1970s. I will discuss some of the properties of Islamic quasicrystalline tilings, and their relation to the Penrose tiling, perhaps the best known quasicrystal pattern.
ics Colloquium
Friday, February 11, 2011
4:00 PM
Physics Building, Room 204
Jim Condon [Host: PQ Hung]
NRAO
"Supermassive Black Holes and the Evolution of Galaxies"
 
 Slideshow (PDF)
ABSTRACT:
The first galaxies were small condensations of baryonic matter that fell into the gravitational potentials of dark-matter halos, and larger galaxies are still being assembled from smaller ones by heirarchical merging. Black holes quickly formed and grew in their centers, and energy feedback from these supermassive black holes (SMBHs) dominated the subsequent growth and stellar composition of large galaxies, making them "red, dead, and elliptical" today. To constrain the role of SMBHs in galaxy evolution we recently measured accurate nuclear masses of six Seyfert galaxies using the Keplerian rotation curves of circumnuclear water masers observed with 0.0003 arcsec resolution. The nuclear mass densities are so high that they are consistent only with supermassive black holes, not dense star clusters. Because nearly all galaxies contain SMBHs, recently merged galaxies should contain inspiraling binary SMBHs that may merge and emit very energetic and anisotropic bursts of gravitational radiation. We recently began the first systematic search for inspiraling, binary, or recoiling SMBHs in hundreds of nearby massive galaxies.
SLIDESHOW:
ics Special Colloquium
Tuesday, February 8, 2011
3:30 PM
Physics Building, Room 204
Chris Neu [Host: Joe Poon]
University of Virginia
"Top Quarks at the Large Hadron Collider: In Pursuit of Truth and its Consequences"
ABSTRACT:
The top quark is a unique member of the collection of known fundamental particles. Its mass is exceedingly large -- nearly that of a single atom of gold -- which is remarkable given that the top quark is considered to be a point particle with no substructure. Further, the top quark decays rapidly, long before having the chance to form a bound state with other quarks. Hence, the study of top-quark decays affords a direct glimpse at the properties of the parent quark itself, allowing measurements of its mass, spin, charge and other properties. Finally, several signatures of new phenomena accessible at particle colliders either suffer from top-quark production as a significant background or contain top quarks themselves. With the advent of the operational era of the Large Hadron Collider (LHC), the Compact Muon Solenoid (CMS) experiment has the opportunity to perform precision measurements of top-quark production and decay for the first time away from Fermilab's Tevatron collider, whose experiments produced the discovery of the top quark in 1994. In this talk I will present some of the first results of the CMS top-quark physics program, results in which members of the University of Virginia CMS group made significant contributions.
ics Colloquium
Friday, February 4, 2011
4:00 PM
Physics Building, Room 204
Israel Klich [Host: Joe Poon]
University of Virginia
"Entanglement and Entropy in many body systems"
ABSTRACT:
As physical systems are cooled down, their properties may no longer be described in classical terms, and we enter a quantum regime. Perhaps the most fascinating quantum property is entanglement. Recently, with understanding of entanglement between a few particles, many-body entanglement has received great interest in such varied fields as condensed matter, cosmology and quantum information. Indeed, the scaling of entanglement in large systems is a sensitive measure of the nature of interactions and phases. In contrast with typical thermodynamical behavior, the entanglement entropy of a sub region in a physical system often grows as it's boundary area, and not as its volume. In this talk, I will describe such “area laws”, their appearance and relation to quantum phase transitions. I will also discuss a yet more detailed analysis of such entanglement, known as entanglement spectrum. Finally, I will exhibit a universal relation between entanglement and statistics of current flowing through a quantum point contact, which provides a way to experimentally measure entanglement entropy.
ics Colloquium
Friday, January 28, 2011
4:00 PM
Physics Building, Room 204
Stephen Martin [Host: Brad Cox]
Northern Illinois University
"Supersymmetry"
 
 Slideshow (PDF)
ABSTRACT:
Supersymmetry is a proposed symmetry of particle physics that relates fermions and bosons to each other. It makes the exciting prediction that for every known elementary particle there is a heavier "superpartner" particle waiting to be discovered. One of these superpartners may be the dark matter required by astrophysical and cosmological observations. I will explain the motivations behind supersymmetry, the predicted properties of the superpartner particles, and review indirect evidence suggesting that at least some of them are likely to be discovered at the Large Hadron Collider within the next few years. Several of the most likely possibilities for the discovery signature for superpartners will be discussed.
SLIDESHOW:
ics Colloquium
Friday, January 21, 2011
4:00 PM
Physics Building, Room 204
Stan Williams [Host: Stu Wolf]
HP
"Memristance and Negative Differential Resistance in Transition Metal Oxides"
ABSTRACT:
Memristive devices are nonlinear dynamical systems that exhibit continuous, reversible and nonvolatile resistance changes that depend on the polarity, magnitude and duration of an applied electric field. The memristive properties of metal/metal oxide/metal (MOM) materials systems were discovered in the 1960s and studied without reaching a consensus on the physical mechanism, while the theoretical foundation of memristance was derived by Chua in 1971 without realizing there were physical examples of this circuit property. Recent studies on the mechanism revealed that memristive switching is caused by electric field-driven motion of charged dopants that define the interface position between conducting and semiconducting regions of the film. There have also been multiple reports of current-controlled negative differential resistance (CC-NDR) in electroformed MOM devices since the early 1960s (e.g. oxides of V, Nb, Ta, Ti and Fe), and there have been a variety of proposals for the physical mechanism. Current work presents persuasive evidence that CC-NDR in these materials is due to a Joule-heating induced metal-insulator transition (MIT). We have found that both memristance and CC-NDR coexist in many transition metal oxides, and the fact that both effects have been called "switching" has caused a great deal of confusion in the literature and prevented comprehensive understanding of these systems. I will explain the origin of both effects in titanium oxides and show some potential applications of combining the two effects in a single nanoscale device.
ics Colloquium
Friday, December 3, 2010
4:00 PM
Physics Building, Room 204
John Brenkus [Host: Lou Bloomfield]
ESPN
"Sport Science and the Perfection Point"
ABSTRACT:
UVA alum John Brenkus will talk about the science of sport, drawing upon his vast experience as the creator, executive producer, and host of the Emmy Award-winning show “Sport Science” on ESPN. He will also discuss his recent book "The Perfection Point," which debuted at #1 on BarnesAndNoble.com when it was released on September 1. On “Sport Science,” Brenkus has the top athletes on the planet into his state-of-the-art laboratory to uncover sports’ biggest myths and mysteries by using cutting-edge technology to measure momentum, friction and the laws of gravity (Sport Science website). Brenkus often wires himself up and steps in the line of fire against pro athletes to see how a “normal” guy stacks up against the pros (human crash-test dummy video).
ics Colloquium
Friday, November 19, 2010
4:00 PM
Physics Building, Room 204
Tomasz Skwarnicki [Host: Brad Cox]
Syracuse University
"Status of LHCb Experiment"
 
 Slideshow (PDF)
ABSTRACT:
LHCb experiment is dedicated to searches for new forces in decays of heavy flavors. I will give an introduction to its physics program. I will discuss the detector performance as measured on the first data, present first results and make projections to near and further future.
SLIDESHOW:
ics Joint Chemistry-Physics Colloquium
Friday, November 12, 2010
4:00 PM
Physics Building, Room 204
Robert Field [Host: Tom Gallagher]
MIT
"CaF: Just Large Enough, and Ca: Even Smaller"
 
 Slideshow (PDF)
ABSTRACT:
CaF is as “not-atom” as a diatomic molecule can be. The core-penetrating and core-nonpenetrating Rydberg states of CaF are observed by two-color Resonance Enhanced Ionization spectroscopy. The observed rovibronic energy levels are input to an energy- and internuclear distance-dependent Multichannel Quantum Defect Theory fit model. The fitted quantum defect matrix, μ(E,R), accounts for nearly all spectra and dynamics of CaF. A “zone of death” is observed, where selection-rule-shattering “indirect” interactions of all Rydberg states with each other, is caused by one repulsive electronic potential curve. A STIRAP-like, multiphoton, chirped pulse, millimeter wave scheme for “jumping over” this zone of death is being developed. Progress toward “pure electronic spectroscopy” and magnetic resonance-like manipulation of molecular Rydberg states requires taking a step that Arthur Schawlow would have liked, back from CaF, with its one atom too many, to the Ca atom. 5 kilo-Debye Rydberg-Rydberg transitions in Ca are directly detected by Free Induction Decay signals, rather than indirectly, via ions or UV fluorescence, in a pulsed supersonic jet.
SLIDESHOW:
ics Colloquium
Friday, November 5, 2010
4:00 PM
Physics Building, Room 204
Bruce Vogelaar [Host: Blaine Norum]
Virginia Tech
"GEM*STAR (Green Energy-Multiplier: Sub-critical, Thermal spectrum, Accelerator-driven, Recycling Reactor)"
 
 Slideshow (PDF)
ABSTRACT:
The world faces serious energy issues, and while nuclear energy could in principle address base-line needs, current methods intrinsically link it to proliferation, waste, high-construction cost, and safety issues. Advances (as confirmed in the 2010 Department of Energy study) in accelerator technology (e.g. SRF at JLab) now allow neutrons to be reliably generated at low-enough cost that a reactor core with a critical mass of fissile material is no longer required. The combination obviates the historical incremental approach to nuclear energy being pursued in this country.

The GEM*STAR approach to such an Accelerator Driven System (ADS) thus intrinsically breaks the links to issues which have crippled the nuclear energy option. It does this by requiring: no enrichment, no reprocessing, no critical-mass on site; and providing far deeper burning with orders-of-magnitude less releasable radioactivity in its core and resulting in far less final waste. The project will demonstrate electricity cheaper than coal, and could beneficially utilize today's LWR spent fuel producing no additional waste.

Results from the recent workshop on ADS (hosted by VT and JLab) along with the new report from the DOE will be presented. GEM*STAR is a project of ADNA Corp. and the Virginia GEM*STAR Consortium (VCU, VT, JLab, UVA).
SLIDESHOW:
ics Colloquium
Friday, October 29, 2010
4:00 PM
Physics Building, Room 204
Olivier Pfister [Host: Joe Poon]
University of Virginia
"Quantum computing over the rainbow"
ABSTRACT:
Quantum computing has attracted much attention over the past sesquidecade because it makes integer-factoring easy, even though that has been a historically (if not provably) hard mathematical problem [1]. Another major interest is the exponential speedup of quantum simulations [2]. The physical implementation of nontrivial quantum computing is an exciting, if daunting, experimental challenge, epitomized by the issues of decoherence and scalability of the quantum registers and processors. In this talk, I will present a novel scheme for realizing a scalable quantum register of potentially very large size, entangled in a "cluster" state, in a remarkably compact physical system: the optical frequency comb (OFC) defined by the eigenmodes of a single optical resonator. The classical OFC is well known as implemented by the femtosecond, carrier-envelope-phase- and mode-locked lasers which have redefined time/frequency metrology and ultraprecise measurements in recent years [3,4]. The quantum version of the OFC is then a set of harmonic oscillators, or "Qmodes," whose amplitude and phase are analogues of the position and momentum mechanical observables. The quantum manipulation of these continuous variables for one or two Qmodes is a mature field. Recently, we have shown theoretically that the nonlinear optical medium of a single optical parametric oscillator (OPO) can be engineered, in a sophisticated but already demonstrated manner, so as to entangle, in constant time, the OPO's OFC into a cluster state of arbitrary size, suitable for one-way quantum computing over continuous variables [5,6]. I will describe the mathematical proof of this result and report on our progress towards its experimental implementation at the University of Virginia.

[1] P. W. Shor, “Algorithms for quantum computation: discrete logarithms and factoring,” in Proceedings, 35th Annual Symposium on Foundations of Computer Science, S. Goldwasser, ed., pp. 124–134 (IEEE Press, Los Alamitos, CA, Santa Fe, NM, 1994).

[2] R. P. Feynman, “Simulating Physics With Computers,” Int. J. Theor. Phys. 21, 467 (1982).

[3] J. L. Hall, “Nobel Lecture: Defining and measuring optical frequencies,” Rev. Mod. Phys. 78, 1279 (2006)

[4] T. W. Hänsch, “Nobel Lecture: Passion for precision,” Rev. Mod. Phys. 78, 1297 (2006).

[5] N. C. Menicucci, S. T. Flammia, and O. Pfister, “One-way quantum computing in the optical frequency comb,” Phys. Rev. Lett. 101, 130501 (2008).

[6] S. T. Flammia, N. C. Menicucci, and O. Pfister, “The optical frequency comb as a one-way quantum computer,” J. Phys. B, 42, 114009 (2009).

ics Colloquium
Friday, October 22, 2010
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, October 15, 2010
4:00 PM
Physics Building, Room 204
Brian Winer [Host: Chris Neu ]
Ohio State University
"Exploring the Universe with Gamma-Rays"
ABSTRACT:
The most energetic phenomena in the cosmos are often revealed through their gamma-ray emissions. Observing gamma-rays up to ~100 GeV requires a space-born observatory. The Fermi Gamma-Ray Space Telescope (FGST) was launched in June 2008 and is beginning its third year of observation of a mission that will last at least 5 years. The primary instrument on FGST is the Large Area Telescope (LAT), which is sensitive to gamma rays from ~20 MeV to over 300 GeV. The current status of the Fermi mission will be discussed along with results from a variety of astrophysical topics including the search for indirect evidence of dark matter.
ics Colloquium
Friday, October 8, 2010
4:00 PM
Physics Building, Room 204
Despina Louca [Host: Joe Poon]
University of Virginia
"Materials world under scrutiny: the view using a very powerful probe"
ABSTRACT:
The emergence of unique physical properties in solids is a manifestation of the coexistence and competition of several degrees of freedom. They are probed by neutrons which provide details on the structure and dynamics. Examples of systems that will be discussed include the magnetoresistive perovskite oxides, bulk metallic alloys, and the new class of superconductors. Understanding the macroscopic functionality of these systems can be potentially very useful for industrial applications.
ics Colloquium
Friday, October 1, 2010
4:00 PM
Physics Building, Room 204
J.J. Suh and Seunghun Lee [Host: Seunghun Lee]
Johns Hopkins University / University of Virginia
"Science, Political Science, and Social Responsibility"
 
 Slideshow (PDF)
ABSTRACT:
J.J. Suh, a political scientist, and S.-H. Lee, a physicist, have been working together to find out what really happened to the South Korean (SK) Navy corvette, the Cheonan, that sank on March 26, 2010 in the Yellow Sea near the sea border with North Korea. On May 20 after almost two months of investigation, the SK-appointed Joint Investigation Group concluded that the Cheonan had been destroyed by a North Korean torpedo. Our close examination of the JIG's evidence, however, shows that its conclusion is scientifically untenable and that the integrity of some of its scientific data has been compromised. This episode clearly illustrates the need of interaction and collaboration between social science and natural science experts when science gets entangled with politics, as it often does in this technologically ever-developing world.
SLIDESHOW:
ics Colloquium
Friday, September 24, 2010
4:00 PM
Physics Building, Room 204
Sebastian Kuhn [Host: Don Crabb]
Old Dominion University
"The Jefferson Lab Program on Inclusive and Semi-Inclusive Deep Inelastic Scattering"
ABSTRACT:
Nucleons (protons and neutrons) play a dual role as the building blocks of atomic nuclei (which constitute nearly all of the mass visible around us) and as stable systems bound by the fundamental strong force of Quantum ChromoDynamics (QCD). When studied with the most powerful microscopes (accelerators) on Earth, nucleons appear as a chaotic jumble of a nearly infinite number of “partons” (quarks, antiquarks and gluons). However, at the more moderate resolution available at Jefferson Lab, a simpler picture emerges: the quantum numbers of the nucleon are due to just three “valence” quarks which carry a large fraction of its energy-momentum, plus a few quark-antiquark pairs and gluons. One of the main research programs at Jefferson Lab is a detailed study of the distribution in space and momentum space of these partons, and their intrinsic spins. Deep inelastic scattering (DIS), where a relatively large momentum and energy is transferred from a scattered electron to the struck nucleon, is a primary tool to unravel this “medium resolution” structure of the nucleon. Additional information becomes available when one detects part of the final-state debris as well as the scattered electron (semi-inclusive DIS). In my talk, I will give some examples of experiments at Jefferson Lab that employ these tools, and explain what we can learn from them.
ics Colloquium
Friday, September 17, 2010
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, September 10, 2010
4:00 PM
Physics Building, Room 204
Chuck Majkrzak [Host: Seunghun Lee]
NIST
"Beauty is only skin deep; probing thin film and membrane structure by neutron reflection"
 
 Slideshow (PDF)
ABSTRACT:
Over the course of the last two decades, neutron reflectometry has become established as an important structural probe of thin films and multilayered composites, most notably of hydrogenous and magnetic materials. As an introduction, the basic principles and typical applications of neutron reflectometry are briefly reviewed. Examples of neutron reflectometry studies of thin film systems of interest in condensed matter physics, chemical physics, and biophysics are presented. In particular, the scattering length density (SLD) depth profile along the surface normal, averaged over in plane, can be deduced from specular neutron reflectivity measurements (wavevector transfer Q normal to the surface). The SLD profile, in turn, is directly related to the corresponding material composition distribution. Under favorable conditions, specular neutron reflectometry can resolve variations in the compositional depth profile on a length scale of the order of a nanometer for a thin film having a single unit repeat, whereas for a periodic multilayered system, the spatial resolution can approach an Angstrom. For specular neutron reflection, the complex reflection amplitude or phase associated with an "unknown" segment of a composite film structure can be determined exactly, using reference segments, and a subsequent direct inversion can be performed, thereby ensuring, in principle, a unique result [1]. Thus, the phasesensitive neutron reflection / inversion process results in a realspace picture without fitting or any adjustable parameters. We will discuss how, because of the onetoone correspondence between the complex reflection amplitude and the SLD, phasesensitive NR can be viewed, in effect, as being equivalent to a realspace imaging process one in which the inversion computation plays an analogous role to that of the brain, for instance, in interpreting the optical image of an object focused on the retina of the eye [2]. In performing phasesensitive reflectivity measurements in practice, what ultimately limits the accuracy and spatial resolution of the depth profile are the maximum range of Q attainable and the statistical uncertainty in the measured reflected intensities. These effects can be analyzed quantitatively [3] and we will consider the spatial resolution currently possible as well as what can be reasonably expected in the future with more advanced neutron sources and instrumentation (e.g., employing polychromatic beams at continuous sources). Finally, we will critically examine a possible alternative approach to performing neutron reflectivity measurements, which involves the quantum phenomenon of "Interaction Free Measurement" (IFM) of the type first proposed by Dicke [4] and realized in rudimentary fashion by Kwiat et al. with visible light [5]. The scheme utilized by Kwiat et al. purportedly optimizes the efficiency for performing an IFM of the reflectivity (or transmission) by application of the quantum Zeno effect (which requires polarized photons or neutrons) within an interferometer.
SLIDESHOW:
ics Colloquium
Friday, September 3, 2010
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, August 27, 2010
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, April 30, 2010
4:00 PM
Physics Building, Room 204
Gerald Dunne [Host: Israel Klich]
University of Connecticut
"The Search for the Heisenberg-Schwinger Effect: Nonperturbative Pair Production from Vacuum"
ABSTRACT:
The Heisenberg-Schwinger effect is the non-perturbative production of electron-positron pairs when an external electric field is applied to the quantum electrodynamical (QED) vacuum. The inherent instability of the quantum vacuum in an electric field was one of the first non- trivial predictions of QED, but the effect is so weak that it has not yet been directly observed. However, new developments in ultra-high intensity lasers come tantalizingly close to opening a new window on this unexplored extreme ultra-relativistic regime. This necessitates a fresh look at both experimental and theoretical aspects of the Heisenberg-Schwinger effect. I review the basic physics of the problem and describe some recent theoretical ideas aimed at making this elusive effect observable, by careful shaping of laser pulses. This is an example of an emerging new field using ultra-intense lasers to probe fundamental problems in particle physics, gravity and quantum field theory.
ics Colloquium
Friday, April 23, 2010
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, April 16, 2010
4:00 PM
Physics Building, Room 204
Paul Chesler [Host: Peter Arnold]
M.I.T.
"Applied string theory -- from gravitational collapse to quark-gluon liquids"
ABSTRACT:
A remarkable result from heavy ion collisions at the Relativistic Heavy Ion Collider is that shortly after a collision, the medium produced behaves as a nearly ideal liquid. The system is very dynamic and evolves from a state of two colliding nuclei to a liquid in a time roughly equivalent to the time it takes light to cross a proton. Understanding the mechanisms behind the rapid approach to a liquid state is a challenging task. In recent years string theory has emerged as a powerful tool to study non-equilibrium phenomena, mapping the (challenging) dynamics of quantum systems onto the dynamics of classical gravitational systems. The creation of a liquid in a quantum theory maps onto the classical process of gravitational collapse and black hole formation. I will describe how one can use techniques borrowed from numerical relativity in astrophysics to study processes which mimic the dynamics of heavy ion collisions.
ics Colloquium
Friday, April 9, 2010
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, April 2, 2010
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, March 26, 2010
4:00 PM
Physics Building, Room 204
Genya Kolomeisky [Host: Dinko Pocanic]
University of Virginia
"Casimir effect due to a single boundary as a manifestation of the Weyl problem"
 
 Slideshow (PDF)
ABSTRACT:
The Casimir self-energy of a boundary is ultraviolet-divergent. In many cases the divergences can be eliminated by methods such as zeta- function regularization or through physical arguments (ultraviolet transparency of the boundary would provide a cutoff). Using the example of a massless scalar field theory with a Dirichlet boundary we explore the relationship between such approaches, with the goal of better understanding the origin of the divergences. We are guided by the insight due to Dowker and Kennedy (1978) and Deutsch and Candelas (1979), that the divergences represent measurable effects that can be interpreted with the aid of the theory of the asymptotic distribution of eigenvalues of the Laplacian first discussed by Weyl. In many cases the Casimir self-energy is the sum of cutoff-dependent (Weyl) terms having geometrical origin, and an "intrinsic" term that is independent of the cutoff. The Weyl terms make a measurable contribution to the physical situation even when regularization methods succeed in isolating the intrinsic part. Regularization methods fail when the Weyl terms and intrinsic parts of the Casimir effect cannot be clearly separated. Specifically, we demonstrate that the Casimir self-energy of a smooth boundary in two dimensions is a sum of two Weyl terms (exhibiting quadratic and logarithmic cutoff dependence), a geometrical term that is independent of cutoff, and a non-geometrical intrinsic term. As by-products we resolve the puzzle of the divergent Casimir force on a ring and correct the sign of the coefficient of linear tension of the Dirichlet line predicted in earlier treatments.
SLIDESHOW:
ics Colloquium
Friday, March 19, 2010
4:00 PM
Physics Building, Room 204
Rob Roser [Host: Chris Neu]
FNAL
"Particle Physics – The Exciting Times at Fermilab"
 
 Slideshow (PDF)
ABSTRACT:
There has never been a more exciting time in Particle Physics. The Tevatron scientists are currently mining huge data samples and expect to double the sample yet again before the current run is through. Meanwhile, the intensity frontier effort is ramping up as Fermilab readies itself for life beyond the energy frontier. In my talk, I will discuss some of the exciting physics results that are currently coming out of the Tevatron program and discuss the future plans of the lab
SLIDESHOW:
ics Colloquium
Friday, March 5, 2010
4:00 PM
Physics Building, Room 204
R. Craig Group [Host: Craig Dukes]
Fermilab
"The Race for the Higgs Boson
(A Tevatron Perspective)"

 
 Slideshow (PDF)
ABSTRACT:
I will begin by motivating the Higgs boson as an important piece of the Standard Model of particle physics that has yet to be experimentally verified. I will then give a short review of high energy colliders and particle detectors and will describe the challenges of discovering a Higgs boson with these machines. I will summarize the status at the Tevatron Collider at Fermilab and the Large Hadron Collider at CERN and portray the excitement at these two labs as the race to discover the Higgs boson tightens up.
SLIDESHOW:
ics Special Colloquium
Monday, March 1, 2010
3:30 PM
Physics Building, Room 204
Victor Gehman [Host: Craig Dukes]
Los Alamos National Laboratory
"Low-Background Searches for Rare Events: The MAJORANA Neutrinoless Double-Beta Decay Experiment, and the CLEAN/DEAP Dark Matter Search"
 
 Slideshow (PDF)
ABSTRACT:
Rare event searches will have a profound impact on the search for physics beyond the Standard Model in the coming years. This is particularly true in searches for neutrinoless double-beta decay and dark matter, and we will discuss one experiment of each type. The MAJORANA experiment will search for neutrinoless double-beta decay in 76Ge by constructing an array of HPGe detectors in ultra-clean electro-formed copper cryostats deep underground. Recent advances in HPGe detector technology, particularly the development of P-type Point Contact (PPC) detectors present excellent new opportunities in identifying and reducing backgrounds to the double-beta decay signal. The CLEAN/DEAP collaboration is fielding MiniCLEAN, a 400-kg, single-phase detector capable of being filled with either liquid neon or argon. MiniCLEAN uses a spherical geometry to maximize light yield and pulse shape analysis techniques to identify nuclear recoil signals and reject electron recoil backgrounds. Careful attention is being paid to reducing the contamination of detector surfaces by environmental radon gas. We will present an overview and highlight recent R&D progress of both experimental programs.
SLIDESHOW:
ics Colloquium
Friday, February 26, 2010
4:00 PM
Physics Building, Room 204
Rocky Kolb [Host: Peter Arnold]
University of Chicago
"Dark Energy: Taking Sides"
 
 Slideshow (PDF)
ABSTRACT:
Dark energy appears to be the dominant component of the present mass-density of the Universe, yet there is no persuasive theoretical explanation for its existence or magnitude. While the simplest explanation might be Einstein's cosmological constant, there are other possibilities, including dynamical dark energy, modification of general relativity, or back reactions of inhomogeneities. After framing the dark-energy problem, I will discuss possible theoretical solutions, as well as an observational program to study the properties of dark energy.
SLIDESHOW:
ics Special Colloquium
Wednesday, February 24, 2010
3:30 PM
Physics Building, Room 204
Kevin Lynch [Host: Craig Dukes]
Boston University
"The MuLan Experiment: Measuring the Muon Lifetime to 1ppm"
 
 Slideshow (PDF)
ABSTRACT:
The Standard Model of Particle and Nuclear physics makes thousands of successful predictions, based on roughly 20 experimentally determined input parameters. Studies on the Electroweak frontier in particular require extremely precise values for a subset of those parameters, including the Fermi Constant. I will describe the MuLan experiment, which has measured the muon lifetime with unprecedented part per million accuracy, improving our knowledge of the Fermi Constant by a factor of 20. I will describe the physics motivation for the measurement, emphasize the subtle design and analysis challenges of a measurement on the precision frontier, and discuss both our published results and current progress towards our ultimate physics goals.
SLIDESHOW:
ics Special Colloquium
Tuesday, February 23, 2010
3:30 PM
Physics Building, Room 204
Mitchell Soderberg
Yale University
"Entering an Era of Precision Neutrino Physics"
 
 Slideshow (PDF)
ABSTRACT:
The discovery just over a decade ago that neutrinos can change identities by oscillating between flavors was a revolutionary change to the Standard Model description of particle physics. This discovery implies that neutrinos are not massless, and that they could play a crucial role in answering some of the most fundamental questions in particle physics, such as whether the observed matter-antimatter asymmetry in the universe can be attributed to CP violating neutrino interactions. Many experiments are currently attempting to solve the remaining mysteries of neutrino behavior, but this is a challenging task due to the elusive nature of these particles. Liquid Argon Time Projection Chambers (LAr TPCs) are ideally suited for the study of neutrino interactions thanks to their precision detection capabilities that make them the modern day equivalent of bubble chambers. In this talk I will motivate the compelling questions in neutrino physics and introduce the LAr TPC technique, highlighting recent work in the development of this technology, including discussion of the ArgoNeuT (Argon Neutrino Test) test-beam project and the MicroBooNE experiment. Finally, I will discuss preliminary ideas for the ultimate experiment that could be conducted at the Deep Underground Science and Engineering Laboratory (DUSEL) in South Dakota as part of a world-class U.S. neutrino program that is currently being planned.
SLIDESHOW:
ics Colloquium
Friday, February 19, 2010
4:00 PM
Physics Building, Room 204
Available
ics Special Colloquium
Wednesday, February 17, 2010
3:30 PM
Physics Building, Room 204
Jennifer Pursley [Host: Craig Dukes]
University of Wisconsin
"Searches for a Standard Model Higgs Boson at the Collider Detector at Fermilab"
ABSTRACT:
In the standard model of particle physics, the Higgs mechanism is theorized to explain the broken symmetry of the electromagnetic and weak forces by giving mass to the W and Z gauge bosons. One consequence of this theory is the existence of another massive elementary particle, called the Higgs boson. While this theory of electroweak symmetry breaking was first introduced in the 1960's, the Higgs boson has yet to be observed experimentally and the theory remains unproven. Finding the Higgs boson is currently one of the primary goals of the Fermilab Tevatron collider and the Large Hadron Collider at CERN. In this colloquium I will start with a brief overview of the standard model of particle physics, the role played by the Higgs mechanism, and previous searches for a Higgs boson. Then I will introduce the Fermilab particle accelerator complex and the Collider Detector at Fermilab experiment, and discuss my own research searching for this elusive piece of the standard model. My focus is on the search for a high-mass Higgs boson, which primarily decays to two W bosons. Although we have not yet discovered a Higgs boson, at the Tevatron we are narrowing the possibilities. Within a few years we should know whether the standard model Higgs boson exists, or if we need a new solution.
ics Colloquium
Friday, February 12, 2010
4:00 PM
Physics Building, Room 204
Austen Lamacraft [Host: Dinko Pocanic]
University of Virginia
"Novel magnetism in ultracold atomic gases"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Friday, January 29, 2010
4:00 PM
Physics Building, Room 204
Diana Vaman [Host: Dinko Pocanic]
University of Virginia
"Strings and QCD"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Wednesday, January 27, 2010
3:30 PM
Physics Building, Room 204
Chris Dawson [Host: Dinko Pocanic]
University of Virginia
"QCD in five dimensions"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Friday, January 22, 2010
4:00 PM
Physics Building, Room 204
Stefan Baessler [Host: Dinko Pocanic]
University of Virginia
"Why does the (free) neutron decay (?)"
ics Colloquium
Friday, December 4, 2009
4:00 PM
Physics Building, Room 204
Kambiz Safinya [Host: Tom Gallagher]
Schlumberger Research
"Meeting Future Energy Demand Through Unconventional Technology "
ABSTRACT:
Crude oil production forecasts point to a drop of 40 M b/d of conventional oil by 2030. Although the financial and economic crisis has driven global energy lower in 2009 for the first time since 1981 on any significant scale, demand will resume its long-term upward trend once the economic recovery gathers pace. By 2030, world primary energy demand is forecast to be around 45% higher than today – this is like adding two more United States to world consumption. There is therefore a drive to develop alternative energy sources as well as unconventional hydrocarbon reserves to replace the lost production from conventional reservoirs. Given that conservative estimates of Heavy Oil reserves approach 6 trillion barrels, and that heavy oil production today is approaching 10% of world production, it is reasonable to suppose that a significant percentage of the production shortfall would be filled through the production of heavy oil. These facts and the significant increase in average crude oil price since the turn of the century have led to an increased level of interest in these types of reservoirs. It is also true that due to the nature of heavy oil, while the reserves are significant, the recoverable reserves are around 5%-7%. The challenge is therefore to develop technologies that can significantly increase the recovery factors of heavy oil reservoirs in an environmentally acceptable manner. This talk will focus on the current approach adopted by industry and the technologies which will be required to address the challenges stated here.
ics Colloquium
Friday, November 20, 2009
4:00 PM
Physics Building, Room 204
RESERVED
ics Colloquium
Friday, November 13, 2009
4:00 PM
Physics Building, Room 204
Tom Gallagher [Host: Seunghun Lee]
University of Virginia
"Nondispersing Rydberg Wavepackets"
 
 Slideshow (PDF)
ABSTRACT:
As first pointed out by Schrodinger, it is possible to make a "classical" atom, one in which the electron moves in an orbit around the nucleus, by creating superpositions of stationary quantum eigenstates. In quantum terms the probability has a moving spatial maximum. The idea lay dormant until the mode locked laser allowed the creation of atomic (and molecular) wavepackets. Such wavepackets usually disperse, that is, they lose their spatial localization after a few orbits. Dispersion can be prevented by applying an weak microwave field at the orbital frequency. The microwave field phase locks the electron's orbital motion, and by altering the microwave field it is possible to alter the electron's orbit. For example, increasing or decreasing the microwave frequency increases the orbital frequency, and changing the microwave polarization from linear to circular produces a circular orbit.
SLIDESHOW:
ics Colloquium
Friday, November 6, 2009
4:00 PM
Physics Building, Room 204
Scott Ransom [Host: PQ Hung]
NRAO
"Detecting Gravitational Waves (and doing other cool physics) with Millisecond Pulsars"
 
 Slideshow (PDF)
ABSTRACT:
The first millisecond pulsar was discovered in 1982. Since that time their use as highly-accurate celestial clocks has improved continually, so that they are now regularly used to measure a variety of general relativistic effects and probe a variety of topics in basic physics, such as the equation of state of matter at supra-nuclear densities. One of their most exciting uses though, is the current North American (NANOGrav) and international (the International Pulsar Timing Array) efforts to directly detect nanohertz frequency gravitational waves, most likely originating from the ensemble of supermassive black hole binaries scattered throughout the universe. In this talk I'll describe how we are using an ensemble of pulsars to try to make such a measurement, how we could make a detection within the next 5-10 years, and how we get a wide variety of very interesting secondary science from the pulsars in the meantime.
SLIDESHOW:
ics Colloquium
Friday, October 30, 2009
4:00 PM
Physics Building, Room 204
Christopher Jarzynski [Host: Austen Lamacraft]
Univ. of Maryland
"Nonequilibrium thermodynamics at the microscale"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Friday, October 23, 2009
4:00 PM
Physics Building, Room 204
Keith Williams [Host: Dinko Pocanic]
University of Virginia
"Nanotube & Graphite based electronics"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Friday, October 16, 2009
4:00 PM
Physics Building, Room 204
Matthew Hastings [Host: Israel Klich]
Station Q, UCSB
"Entropy in Quantum Information Theory and Condensed Matter Physics"
 
 Slideshow (PDF)
ABSTRACT:
While entropy was introduced in thermodynamics to describe heat engines, its applications have spread to widely different areas. I will talk about recent research on two such problems. The first is a problem in information theory: how much information can we send over a noisy communication channel, given that the world is described by quantum mechanics? I will explain the so-called "additivity conjecture", which was a proposed way to calculate the communication capacity of such a channel, and I will explain my recent result disproving this conjecture, showing that we can use entanglement to boost communication capacity. The second problem is in quantum systems far from equilbrium. Here I will describe how entropy can arise from quantum entanglement, and I will discuss novel simulation algorithms and future experiments probing the relaxation back to local thermal equilibrium.
SLIDESHOW:
ics Colloquium
Friday, October 9, 2009
4:00 PM
Physics Building, Room 204
Eric Prebys [Host: Craig Dukes]
Fermilab
"Energy: No Such Thing as a Free Lunch"
 
 Slideshow (PDF)
ABSTRACT:
Mankind has had a long obsession with the quest for limitless or virtually limitless sources of energy. This quest did not stop with the advent of modern physics, but much of it moved out of the realm of science and into the realm of pseudo-science. Today, "free energy" is a thriving, multi-million dollar business. It involves a colorful cast of characters that range from the sincerely self-deluded to outright charlatans. The fact their claims are given greeted with such credulity by both the public and the news media has profound implications about the general state of scientific understanding in our society.
SLIDESHOW:
ics Colloquium
Friday, October 2, 2009
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, September 25, 2009
4:00 PM
Physics Building, Room 204
Jim Condon [Host: PQ Hung]
NRAO
"Dark Energy and the Hubble Constant"
 
 Slideshow (PDF)
ABSTRACT:
Dark energy dominates the expansion of the universe and will determine its ultimate fate. The best complement to cosmic microwave background data for constraining the nature of dark energy is an accurate measurement of the current expansion rate (Hubble constant). The goal of the Megamaser Cosmology Project is to measure the Hubble constant by using the Green Bank Telescope and the Very Long Baseline Array to discover and image 22 GHz water masers orbiting the nuclei of Seyfert galaxies. We can show that these compact nuclei contain supermassive black holes, not just dense clusters of stars, and determine their masses. In the past year we improved our measurement of the angular-size distance to the galaxy UGC 3789, imaged four more masing galaxies, and derived a preliminary estimate for the Hubble constant.
SLIDESHOW:
ics Colloquium
Friday, September 18, 2009
4:00 PM
Physics Building, Room 204
Hugh Montgomery [Host: Gordon Cates]
Director of JLab
"Exploring the Nature of Matter: Jefferson Lab and its plans"
 
 Slideshow (PDF)
ABSTRACT:
Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of the premier facilities for nuclear and hadronic physics in the world. With high luminosity and high polarization continuous wave electron beams, the 6 GeV physics program has produced exciting results during the past decade. Currently the laboratory is executing an upgrade of the accelerator from 6 GeV to 12 GeV: this project was recommended as the top priority in the most recent US nuclear physics long-range plan. The upgrade, which also includes changes to the experimental facilities, will open new avenues of investigation. Beyond this upgrade Jefferson Lab is preparing the case for a future Electron Ion Collider.
SLIDESHOW:
ics Colloquium
Friday, September 11, 2009
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, September 4, 2009
4:00 PM
Physics Building, Room 204
Young-kee Kim [Host: Seunghun Lee]
Deputy Director, Fermilab/University of Chicago
" E = mc^2, High energy and intensity opens windows on the world"
 
 Slideshow (PDF)
ABSTRACT:
The profound discovery of Einstein a century ago, that particles can both be made from energy and disappear back into energy, inspires the experiments that provide our knowledge of the smallest building blocks of matter. The experiments, done at enormous energy and intensity frontier accelerators, have led to a consistent theory of the origins of our world up to a certain point. However, at an energy scale not far above what we can attain at existing accelerators, this picture is predicted to break down. Moreover, the theory of the very small is intimately connected to cosmology -- the ultimate cause and structure of our universe. Cosmological observations again point to the need for a new theory in this energy range. In this colloquium, I will trace out the path from where we are and what we need to do to take the next step towards understanding the nature of space and time. The discovery of new particles or new laws at energy and intensity frontier accelerators will open up windows on this world.
SLIDESHOW:
ics Colloquium
Friday, August 28, 2009
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, May 1, 2009
4:00 PM
Physics Building, Room 204
Zlatko Tesanovic [Host: Seunghun Lee]
Johns Hopkins University
"Superconductivity at the Dawn of the Iron Age"
ABSTRACT:
Recent discovery of iron-based high temperature superconductors hints at a new pathway to the room temperature superconductivity. The new materials feature FeAs layers instead of the signature CuO2 planes of much-studied cuprate superconductors. The antiferromagnetism also appears to be involved, although the d-electrons in FeAs seem considerably more mobile than their cuprate cousins. This high mobility, facilitated by a large overlap between atomic orbitals of Fe and As, plays a crucial role in warding off Hund's rule and the large local moment magnetism of Fe ions, the archrival of superconductivity. I will present a pedagogical review of the current status of the field, highlighting similarities and differences between iron pnictides and cuprates, and emphasizing the importance of the multiband nature of magnetism and superconductivity in these new materials.
ics Colloquium
Friday, April 24, 2009
4:00 PM
Physics Building, Room 204
George Gollin [Host: Craig Dukes ]
University of Illinois
"Academic Fraud and a Calculus of Death"
ABSTRACT:
For a price, it is possible to acquire unearned academic degrees from non-existent universities that market diplomas over the internet. The most sophisticated of these diploma mill cartels, based in Spokane, Washington, used the turmoil in Western Africa to foster the illusion of recognition and accreditation by the Republic of Liberia. But these credentials were obtained through payments to government officials, and were no more legitimate than the supporting web of fake diplomatic missions, schools, accreditors, and credential evaluators created by the "Saint Regis University" group. Their operation spanned at least eighteen states and twenty-two countries, and their stable of degree mills included over seventy non-existent schools selling degrees in medicine, nursing, nuclear and aeronautical engineering, addiction counseling, and special education, among other fields. Falsely identifying herself as a Liberian official, the principal owner of St. Regis wrote to the University of Illinois in 2003 threatening legal action over information I had posted to a university web page. The resulting brawl led to a multi-agency federal criminal investigation: prosecutors indicted the owners and staff of St. Regis for mail fraud, wire fraud, money laundering, and bribery of foreign officials in late 2005. All eight defendants pled guilty; five began serving prison terms in late 2008. This is a serious issue. The investigation revealed an alarming mix of consumer protection, public safety, and national security issues raised by the activities of the Saint Regis group. In addition, the delay in Liberia's recovery from two decades of civil war, due to the corrupting influences of the St. Regis organization, convolves with Liberia's infant mortality rate in a ghastly calculus of death. And we now see a next-generation diploma mill, having learned from St. Regis' mistakes, attacking the higher education systems in the two African nations immediately to the west of Darfur. We are beginning to make progress. New federal legislation intended to begin the long process of obliterating the diploma mill industry is a direct result of the St. Regis case. Several states have also drafted new laws, or otherwise tightened their oversight of degree providers. But it is an international problem of great complexity, and we are slow to respond. I will tell you stories, all of which are true.
ics Colloquium
Friday, April 17, 2009
4:00 PM
Physics Building, Room 204
Brad Marston [Host: Paul Fendley]
Brown University
"The Quantum Mechanics of Global Warming"
 
 Slideshow (PDF)
ABSTRACT:
Quantum mechanics plays a crucial, albeit often overlooked, role in our understanding of the Earth's climate. In this talk three well known aspects of quantum mechanics are invoked to present a simple physical picture of what may happen as the concentrations of greenhouse gases such as carbon dioxide continue to increase. Historical and paleoclimatic records are interpreted with some basic astronomy, fluid mechanics, and the use of fundamental laws of physics such as the conservation of angular momentum. I conclude by discussing some possible ways that theoretical physics might be able to contribute to a deeper understanding of climate change.
SLIDESHOW:
ics Colloquium
Friday, April 10, 2009
4:00 PM
Physics Building, Room 204
Kirill Shtengel [Host: Israel Klich]
UC Riverside
"Non-Abelian anyons: New particles for less than a billion"
ABSTRACT:
The notion of quantum topological order has been a subject of much interest recently, in part because it falls outside of the well-established Landau paradigm whereby states of matter are classified according to their broken symmetries. Topologically ordered phases cannot be described by any local order parameter, yet they have many peculiar properties clearly distinguishing them from the conventionally disordered phases. For example, in two dimensions, they may support anyonic excitations - the quasiparticles that are neither bosons nor fermions. Moreover, anyons with *non-Abelian* braiding statistics are expected to occur, particularly in the fractional quantum Hall regime. Interesting in their own right, such systems may also provide a platform for topological quantum computation. Interferometric experiments are likely to play a crucial role in both determining the non-Abelian nature of these states and in their potential applications for quantum computing. I will discuss solid state interferometers designed to detect such non-Abelian quasiparticle statistics. Should these experiments succeed, such interferometers could also become key elements in a topological quantum computer.
ics Colloquium
Friday, April 3, 2009
4:00 PM
Physics Building, Room 204
Mike Norman [Host: Despina Louca]
Argonne National Laboratory
"High Temperature Superconductivity - After 23 years, where are we at? "
 
 Slideshow (PDF)
ABSTRACT:
The field of high temperature cuprate superconductivity remains as controversial as ever. Although certain matters have been settled, for instance the symmetry of the order parameter, there is no accepted microscopic framework for describing these materials. This might seem surprising given their relatively simple electronic structure, but the issues involved touch some of the most fundamental ones facing physics - in particular the problem of how to properly treat strong correlations between electrons. In this talk, I will discuss the progress that has been made, but also the many issues that will have to be resolved before we can say that we have "solved" the cuprate problem.
SLIDESHOW:
ics Colloquium
Friday, March 27, 2009
4:00 PM
Physics Building, Room 204
Thad Walker [Host: Tom Gallagher]
University of Wisconsin
"Quantum Manipulation of Neutral Atoms Without Forces"
 
 Slideshow (PDF)
ABSTRACT:
Interactions between pairs of Rydberg atoms can be so strong that the energy level structure of one atom is dramatically altered by the presence of a second atom 10 microns away. This "Rydberg blockade" is predicted to allow conditional quantum manipulation of individual atoms based on the quantum state of a distant neighboring atom. When successful, the resulting entanglement process occurs without the atoms experiencing any significant interatomic forces. I will describe experiments at the University of Wisconsin that demonstrate blockade-conditioned coherent evolution of a single Rb atom based on the quantum state of a second atom 11 microns away. Extensions of these ideas to deterministic single atom and single photon sources with atomic ensembles will be presented.
SLIDESHOW:
ics Colloquium
Friday, March 20, 2009
4:00 PM
Physics Building, Room 204
Craig Dukes [Host: Jongsoo Yoon]
University of Virginia
"Beyond E=mc^2: Using Rare Particle Decays to Probe the Energy Frontier"
 
 Slideshow (PDF)
ABSTRACT:
Although there is great excitement in particle physics these days, with the advent of the Large Hadron Collider upon us and the great discoveries we hope it will bring, for the first time in some seventy years there are no plans for any new accelerators to take us to the next energy regime. So we will need to look for tiny indirect signs such as rare particle decays in order to find out what may be lurking beyond what we can directly produce in collisions at particle accelerators. There is a long history of such searches for new physics, a history that predates particle physics itself. I will show how such searches will probe mass scales unobtainable by any conceivable particle accelerator and describe the types of accelerators and experiments that are being planned, in particular a very high-sensitivity search for lepton flavor violation in muon decays.
SLIDESHOW:
ics Colloquium
Thursday, March 12, 2009
2:00 PM
MEC, Room 205
Nathan Guisinger [Host: Keith Williams]
Argonne
"Graphene-Based Electronics"
ics Colloquium
Friday, February 27, 2009
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, February 20, 2009
4:00 PM
Physics Building, Room 204
Richard York [Host: Blaine Norum]
MSU
"FRIB: A New Accelerator Facility for the Production of Radioactive Beams"
ABSTRACT:
The 2007 Long Range Plan for Nuclear Science had as one of its highest recommendations the “construction of a Facility for Rare Isotope Beams (FRIB) a world-leading facility for the study of nuclear structure, reactions, and astrophysics. Experiments with the new isotopes produced at FRIB will lead to a comprehensive description of nuclei, elucidate the origin of the elements in the cosmos, provide an understanding of matter in the crust of neutron stars, and establish the scientific foundation for innovative applications of nuclear science to society.” A heavy-ion driver driver linear accelerator (linac) will be used to provide stable beams of >200 MeV/u at beam powers up to 400 kW that will be used to produce rare isotopes. Experiments can be done with rare isotope beams at velocities similar to the linac beam, at near zero velocities after stopping in a gas cell, or at intermediate (0.3 to 10 MeV/u) velocities through reacceleration. An overview of the science and the design proposed for implementation on the campus of Michigan State University leveraging the existing infrastructure will be presented.
ics Colloquium
Friday, February 13, 2009
4:00 PM
Physics Building, Room 204
Kent Paschke [Host: Dinko Pocanic]
University of Virginia
"Electrons and Mirror Symmetry"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Friday, February 6, 2009
4:00 PM
Physics Building, Room 204
Xiaochao Zheng [Host: Dinko Pocanic]
University of Virginia
"Studying strong and electroweak interactions using electron scattering at Jefferson Lab"
 
 Slideshow (PDF)
ABSTRACT:
I will present two research topics of Jefferson Lab: The first topic is focused on a planned precision measurement of the parity violating asymmetry in e-2H deep inelastic scattering (PVDIS). This asymmetry is sensitive to the electroweak neutral coupling $C_{2q}$ of the Standard Model. The experiment (E08-011) has been approved to run from November to December 2009. I will present the progress in the preparation of E08-011, in particular the development of a new fast-counting DAQ system. The second topic is on the extraction of double and single-target spin asymmetries of pion electro-production using JLab Hall B(CLAS)/EG4 data. We expect to extract these asymmetries in the very low $Q^2$ region Q^2<0.1 (GeV/c)^2. These data will provide important inputs to global analyses of the nucleon resonance structure. Preliminary results using a 3 GeV beam and a NH$_3$ target will be presented.
SLIDESHOW:
ics Colloquium
Friday, January 30, 2009
4:00 PM
Physics Building, Room 204
Available [Host: Jongsoo Yoon]
ics Colloquium
Friday, January 23, 2009
4:00 PM
Physics Building, Room 204
Charlie Kane [Host: Israel Klich]
U. Penn
"The Quantum Spin Hall Effect and Topological Band Theory"
ABSTRACT:
A topological insulator is a material with a bulk excitation gap generated by the spin orbit interaction, which is topologically distinct from an ordinary insulator. This distinction - characterized by a topological invariant - necessitates the existence of gapless metallic states on the sample boundary, which have important implications for electronic transport. In two dimensions, the topological insulator is a quantum spin Hall insulator, which is a close cousin of the integer quantum Hall state. In this talk we will outline our theoretical discovery of this phase and describe two recent experiments in which the signatures of this effect have been observed. (1) Transport experiments on HgTe/HgCdTe quantum wells have demonstrated the existence of the edge states predicted for the quantum spin Hall insulator. (2) Photoemission experiments on the semiconducting alloy Bi_{1-x} Sb_x have observed the signature of the gapless surface states predicted for a three dimensional topological insulator. We will close by arguing that the proximity effect between an ordinary superconductor and a 3D topological insulator leads to a novel two dimensional interface state which may provide a new venue for realizing proposals for topological quantum computation.
ics Colloquium
Friday, January 16, 2009
4:00 PM
Physics Building, Room 204
RESERVED
ics Colloquium
Friday, December 5, 2008
4:00 PM
Physics Building, Room 204
Stefan Baessler [Host: Dinko Pocanic]
University of Virginia
"The study of neutron quantum states in the Earth's gravitational field"
 
 Slideshow (PDF)
ABSTRACT:
I will discuss the discovery and characterization of gravitational bound neutron states. In the previous experiments, the lowest neutron quantum states in the gravitational potential were distinguished and characterized by a measurement of their spatial extent. The future detection of resonant transitions between these neutron quantum states with the help of the GRANIT spectrometer (under construction) promises to give further and more precise information. Here, transitions between different quantum states induced by RF pulses shall be observed. These measurements are not only demonstrations of standard quantum mechanics. I will discuss applications of these measurements in the search for spin-dependent short-range interactions.
SLIDESHOW:
ics Colloquium
Friday, November 21, 2008
4:00 PM
Physics Building, Room 204
Pierre Meystre [Host: Tom Gallagher]
University of Arizona
"Cavity optomechanics"
 
 Slideshow (PDF)
ABSTRACT:
Recent experimental advances in laser cooling have brought macroscopic oscillators closer than ever before to operating in the quantum regime. Fundamental interest in this frontier lies in the fact that quantum mechanics has never been tested at such a macroscopic scale, particularly with respect to counter-intuitive effects such as superposition and entanglement. From a more practical point of view, mechanical oscillators operating in the quantum offer considerable promise as sensors whose precision is fundamentally restricted by quantum mechanics. The talk will present a broad review of the basic principles of the laser cooling of opto-mechanical cantilevers, and then turn to a discussion of some possible applications in the coherent control of atomic and molecular systems.
SLIDESHOW:
ics Colloquium
Friday, November 14, 2008
4:00 PM
Physics Building, Room 204
Andy Sandorfi [Host: Blaine Norum]
JLab
"Novel Physics with Frozen-Spin Polarized Solid Hydrogen"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Friday, November 7, 2008
4:00 PM
Physics Building, Room 204
Carl Caves [Host: Olivier Pfister]
University of New Mexico
"Quantum-limited measurements: One physicist's crooked path from quantum optics to quantum information"
 
 Slideshow (PDF)
ABSTRACT:
Quantum information science has changed our view of quantum mechanics. Originally viewed as a nag, whose uncertainty principles restrict what we can do, quantum mechanics mechanics is now seen as a liberator, allowing us to do things, such as secure key distribution and efficient computations, that could not be done in the realistic world of classical physics. Yet there is one area, that of quantum limits on high-precision measurements, where the two faces of quantum mechanics remain locked in battle. Using my own career as a convenient backdrop, I will trace the history of quantum-limited measurements, from the use of nonclassical light to improve the phase sensitivity of an interferometer, to the modern perspective on how quantum entanglement can be used to improve measurement precision, and finally to how to do quantum metrology without entanglement.
SLIDESHOW:
ics Colloquium
Friday, October 31, 2008
4:00 PM
Physics Building, Room 204
Bellave Shivaram [Host: Jongsoo Yoon]
University of Virginia
"SCIENTIFIC CHALLENGES IN HYDROGEN STORAGE: BREAKTHROUGHS AT UVa"
 
 Slideshow (PDF)
ABSTRACT:
I will describe results of recent experiments at UVa which have revealed that hydrogen storage upto 14 wt.% can be achieved. This is a world record for hydrogen uptake. I will also review the significant scientific challenges that remain and discuss possible solutions. Related work in other laboratories will be discussed as well.
SLIDESHOW:
ics Colloquium
Thursday, October 30, 2008
4:00 PM
Physics Building, Room 204
Seunghun Lee [Host: Dinko Pocanic]
University of Virginia
"Magnetic field-induced phase transition in a quantum gapped system: is the Bose-Einstein condensation concept useful?"
ics Colloquium
Friday, October 24, 2008
4:00 PM
Physics Building, Room 204
Mark Adams [Host: Bascom Deaver]
Vice President, ITT Corporation
"Physics –Fundamentals for Business"
ABSTRACT:
Mr. Adams discusses a number of poignant experiences as an undergraduate Physics major at UVA and traces how these lessons have been foundational in his approach to building businesses throughout his career. The technical and operational challenges of remaking a failed $7B company with annual losses exceeding $1B are described from the perspective of a closet physicist. Mr. Adams relates his physics inspired approaches – ranging from the futile to the fruitful – to creating an organization that supports over 300,000 subscribers in over 100 countries worldwide. He also discusses the physics behind his second business startup, which has grown to over a hundred professionals with locations in three states.
ics Colloquium
Friday, October 17, 2008
4:00 PM
Physics Building, Room 204
Costas Soukoulis [Host: Michael Fowler]
Ames Lab
"Bending Back the Light: The science of negative refraction"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Friday, October 10, 2008
4:00 PM
Physics Building, Room 204
Available [Host: ]
ics Colloquium
Friday, October 3, 2008
4:00 PM
Physics Building, Room 204
Eun-Suk Seo [Host: Seunghun Lee]
University of Maryland
"Detecting Cosmic Messengers with Antarctic Balloon Flights "
ABSTRACT:
Cosmic rays bring us information about physical processes that accelerate particles to relativistic energies, the effects of those particles in driving dynamical processes in our Galaxy, and the distribution of matter and fields in interstellar space. These cosmic messengers can far exceed the energies produced by man-made particle accelerators on Earth. Balloon-borne instruments configured with particle detectors are flown in Antarctica to study cosmic-ray origin, acceleration and propagation. They are also used to explore a possible supernova acceleration limit and to search for exotic sources such as dark matter and antimatter. Our on-going efforts with balloon-borne experiments will be presented and challenges of extending precision measurements to highest energy practical will be discussed.
ics Colloquium
Friday, September 26, 2008
4:00 PM
Physics Building, Room 204
Oded Kishony [Host: Keith Williams]
Charlottesville, Violinmaker
"The Ancient Science of Violinmaking"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Friday, September 19, 2008
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, September 12, 2008
4:00 PM
Physics Building, Room 204
Alexander Kusenko [Host: PQ Hung]
UCLA
"Neutrinos, and the dark side of the light fermions"
 
 Slideshow (PDF)
ABSTRACT:
The past decade has been marked by some remarkable discoveries in the neutrino physics: the particles once believed to be massless have turned out to be massive and have shown evidence of lepton family number violation, as well as other interesting phenomena. While this is exciting, the future may hold even more dramatic discoveries, the hints for which begin to appear in astrophysics and cosmology. The observed neutrino masses imply the existence of some yet undiscovered "right-handed" states, which can be very massive and unreachable, but which can also be light enough to constitute the cosmological dark matter and to account for a number of astrophysical phenomena, from supernova asymmetries and the pulsar kicks to the peculiarities in the reionization and formation of the first stars. I will review the recent progress in neutrino physics, as well as the clues that may lead to future discoveries.
SLIDESHOW:
ics Colloquium
Friday, September 5, 2008
4:00 PM
Physics Building, Room 204
Michael Raymer [Host: Olivier Pfister]
University of Oregon
"Photon Wave Mechanics and Spin-Orbit Interaction in Single Photons"
 
 Slideshow (PDF)
ABSTRACT:
We often use the term “photon” in reference to individual quantum objects, or particles of light, rather than as excitations of the electromagnetic field. Yet, quantum mechanics textbooks contain no satisfactory wave equation for the photon wave function. I review the analog of the Dirac equation for a photon, which completely describes the evolution of the photon’s quantum wave function in coordinate space. Single photons carry orbital angular momentum as well as spin angular momentum. When a single photon travels in a multimode optical fiber, its spin and orbital angular momenta interact, modifying the shape of the photon wave function as it travels. Close analogy of this behavior can be found with that of an electron in a cylindrical potential, in spite of the fact that a photon has no magnetic moment. We are carrying out related experiments to illustrate the usefulness of the photon wave function concept.
SLIDESHOW:
ics Colloquium
Friday, August 29, 2008
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, April 25, 2008
4:00 PM
Physics Building, Room 204
Kyungwha Park [Host: Keith Williams]
Virginia Tech
"Interaction between a molecular magnet monolayer and a metallic surface"
 
 Slideshow (PDF)
ABSTRACT:
Over the past decade, molecular magnets or single-molecule magnets have drawn considerable attention due to observed magnetic quantum tunneling and interference and a possibility of using them for information storage or devices. There have been so far significant efforts to build and characterize thin films or monolayers of single-molecule magnets on surfaces or single-molecule magnets bridged between electrodes. However, there is need to understand changes of the properties of single-molecule magnets in those environments using atomic-scale simulations. In this regard, we simulate, within density-functional theory, a nanostructure in which prototype Mn12 molecules are adsorbed via a thiol group onto a gold surface. Based on a supercell calculation, we investigate how much charge and spin are transferred between a Mn12 molecule and the metal surface. In addition, we compare the electronic structure and magnetic properties of the nanostructure with those of an isolated Mn12 molecule in the absence and presence of spin-orbit interaction.
SLIDESHOW:
ics Joint Astronomy-Physics-NRAO Colloquium


Friday, April 18, 2008
4:00 PM
Physics Building, Room 203
Alan Watson [Host: Brad Cox]
Leeds University, England
"Is the search for the origin of the highest energy cosmic rays over?"
 
 Slideshow (PDF)
ABSTRACT:

This question can now be asked because of two results obtained using data recorded at the Pierre Auger Observatory. It has been established, at the 6-sigma level, that the flux of the highest energy cosmic rays is suppressed at energies beyond 5 x 10 19 eV and that above this energy an anisotropy in the arrival directions of the particles is apparent. The arrival directions appear to be associated with sources within the GZK horizon (z ~ 0.018 or 75 Mpc). From these observations it seems probable that we have observed the long-sought Greisen-Zatsepin-Kuzmin effect, demonstrating that ultra-high energy cosmic rays are of extragalactic origin. It is also probable that these particles are protons, thus offering the possibility of insights into features of particle physics at centre-of-mass energies 30 times greater than will be reached at the LHC. Preliminary conclusions from studies of detailed features of extensive air showers suggest that extrapolations from Tevatron energies may not be what have been anticipated hitherto. Much further work remains to be done.

SLIDESHOW:
ics Hoxton Lecture
Thursday, April 17, 2008
7:30 PM
Physics Building, Room Chemistry Building, Room 402
Alan Watson [Host: Physics Department]
University of Leeds, United Kingdom
"The Birth of Cosmic Ray Astronomy on the Argentine Pampas"
ics Special Colloquium
Tuesday, April 15, 2008
4:00 PM
Physics Building, Room 204
Daniel Eisenstein [Host: Dinko Pocanic]
University of Arizona
"Dark Energy and Cosmic Sound"
ABSTRACT:
I present galaxy clustering results from the Sloan Digital Sky Survey that reveal the signature of acoustic oscillations of the photon-baryon fluid in the first million years of the Universe. The scale of this feature can be computed and hence the detection in the galaxy clustering serves as a standard ruler, giving a geometric distance to a redshift of 0.35. I will discuss the implications of this measurement for the composition of the universe, including dark energy and spatial curvature. I will close with a more general discussion of SDSS-III, a new collaborative project that will feature a large redshift survey aimed at refining the acoustic oscillation distance scale to 1% as well as surveys for extrasolar planets and the structure of the Milky Way.
ics Colloquium
Friday, April 11, 2008
4:00 PM
Physics Building, Room 204
John Arrington [Host: Nilanga Liyanage]
Argonne National Lab
"Nucleon Form Factors...50 Years Later"
ABSTRACT:
The structure of the proton and neutron can be expressed in terms of the electric and magnetic form factors which can be measured from elastic electron-proton scattering. Fifty years ago, the first electron scattering measurements of the proton form factors started the process of mapping out the distribution of charge and magnetization of the proton. Four decades of measurements gave us a simple picture of the nucleon, but our understanding was severely limited by the experimental techniques and theoretical understanding. The last ten years as provided several new experimental and theoretical techniques, giving us a much clearer picture of nucleon structure, and providing a few surprises along the way.
ics Special Colloquium
Monday, April 7, 2008
4:00 PM
Wilsdorf Hall, Room Atrium
Ned Seeman [Host: Keith Williams]
NYU
"Nanoscale Assembly with DNA"
ics Colloquium
Friday, April 4, 2008
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, March 28, 2008
4:00 PM
Physics Building, Room 204
Seonho Choi [Host: Nilanga Liyanage]
Seoul National University
"Probing Nucleons Inside Nucleus"
ABSTRACT:
The interior world of the nucleus is still a mystery in nuclear physics. While it is well known that the nucleus is made of nucleons, their properties inside the nucleus are still a big puzzle. There has been a series of experiments to probe the nucleons inside the nucleus. However, the results are still controversial. One main remaining question is regarding the Coulomb Sum Rule (CSR). The colloquium will cover the basic concept of probing microscopic world with high energy electron beams, the key issues of the CSR problem and the recent, new experiment at Jefferson Lab to study the CSR problem.
ics Colloquium
Friday, March 21, 2008
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, March 14, 2008
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, February 29, 2008
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, February 22, 2008
4:00 PM
Physics Building, Room 204
Benjamin Kilminster [Host: Brad Cox]
Ohio State University
"Fermilab's race for the Higgs boson"
ABSTRACT:
One of the most important mysteries in our understanding of the universe is how elementary particles acquire mass. Our best explanation for this requires the existence of a particle called the Higgs boson, which has not yet been directly observed. Particle physicists at Fermilab, near Chicago, are currently capable of producing and detecting Higgs bosons from collisions of matter and antimatter at very high energies. I will explain what exactly these physicists are looking for, and present the experimental challenges involved in a few particular methods for differentiating Higgs bosons from other background processes. Finally, I will discuss future prospects for Higgs boson discovery at Fermilab, as well as the discovery potential of future experiments.
ics Colloquium
Wednesday, February 20, 2008
3:30 PM
Physics Building, Room 204
Christopher Neu [Host: Brad Cox]
University of Pennsylvania
"W Bosons and b Quarks at the Tevatron: Understanding the Haystack to Help Find the Needle"
 
 Slideshow (PDF)
ABSTRACT:
Particle physics is at the threshold of an exciting new era. A crucial experimental pursuit is the search for and observation of the Higgs boson, a prominent missing piece in the widely successful standard model of the fundamental world. Searches at the Tevatron proton-antiproton collider in Illinois are closing in on the Higgs, while experiments at the new Large Hadron Collider in Switzerland are scheduled to begin operations later this year. One of the main signatures for the Higgs contains a W boson and one or more b quarks. However, this signature is shared by more common electroweak and strong processes that have not been determined precisely by experiment until now. Herein I will present a new measurement by CDF of W boson and b quark production. This measurement will contribute to improvements in the theoretical models, and I will discuss how this result can be used to sharpen searches for the Higgs and for physics beyond the standard model at both the Tevatron and the Large Hadron Collider.
SLIDESHOW:
ics Colloquium
Tuesday, February 19, 2008
3:30 PM
Physics Building, Room 204
Sabine Lammers [Host: Brad Cox]
Columbia University
"The Quest for the SM Higgs"
 
 Slideshow (PDF)
ABSTRACT:
The Standard Model predicts the existence of one final particle, the Higgs Boson, which is the physical manifestation of spontaneous symmetry breaking as a mechanism for electroweak symmetry breaking, and is responsible for the masses of the known gauge bosons. Without the Higgs, the Standard Model is certainly incorrect or at least incomplete. We are at a precipice in the study of particle physics today because the answer to the question of the existence of the Higgs is about to be revealed. Constraints from precision LEP electroweak data indicate that the Higgs is light, making it within reach of observation by modern high energy particle colliders. I will discuss the state-of-the-art searches for the Standard Model Higgs Boson at the Tevatron and the plans for searches at the LHC. In particular, I will highlight the search techniques that are relevant at each collider and how Higgs searches at the LHC can benefit from knowledge gained at the Tevatron.
SLIDESHOW:
ics Colloquium
Friday, February 15, 2008
4:00 PM
Physics Building, Room 204
Marvin Blecher [Host: Blaine Norum]
Virginia Tech
"A More Accurate Measurement of Pion to Positron Decay"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Wednesday, February 13, 2008
3:30 PM
Physics Building, Room 204
Zelimir Djurcic [Host: Brad Cox]
Columbia University
"Searching for Physics Beyond the Standard Model with Neutrinos"
 
 Slideshow (PDF)
ABSTRACT:
Although there has been tremendous progress over the past decade, many basic properties of neutrinos are still unknown and the possibility of future surprises remains strong. Recent neutrino experiments have conclusively observed that neutrinos have non-zero masses and that neutrinos change from one flavor to another. The MiniBooNE experiment at Fermilab recently presented its first neutrino oscillation results, where no significant excess of events was observed at higher energies, but a sizeable excess of events was observed at lower energies. The lack of a significant excess at higher energies allowed MiniBooNE to rule out simple 2-neutrino oscillations as an explanation of the LSND signal; however, the excess at lower energies is presently unexplained. Other data sets, including the NuMI, antineutrino, and SciBooNE data, should allow the collaboration to determine whether the lower-energy excess is due to background or to new physics.
SLIDESHOW:
ics Colloquium
Friday, February 8, 2008
4:00 PM
Physics Building, Room 204
Andrew Askew [Host: Brad Cox]
Florida State University
"Life, the Universe, and Electroweak Symmetry Breaking"
 
 Slideshow (PDF)
ABSTRACT:
One of the largest remaining questions in particle physics is the mechanism by which the W and Z bosons gain their mass. In the Standard Model of Particle Physics, this electroweak symmetry breaking occurs via the Higgs mechanism, though this remains experimentally unverified. I will overview this question and then concentrate on how diboson production and kinematics can give us information about this symmetry breaking. Experimental studies of boson pairs produced at the Tevatron and observed at the D0 experiment will be presented, ending with prospects for further study at the LHC.
SLIDESHOW:
ics Colloquium
Friday, February 1, 2008
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, January 25, 2008
4:00 PM
Physics Building, Room 204
Bernard Gerstman [Host: Art Brill]
Florida International University
"Protein Folding: Energy, Entropy, and Prion Diseases"
 
 Slideshow (PDF)
ABSTRACT:
Living systems are the epitome of self-organized complexity. The self-organization occurs on all scales, from the molecular up to the organismal level. The machines responsible for maintaining organization are protein molecules that receive energy and convert it to work. However, protein molecules themselves must self-organize into highly specific shapes. The folding of proteins is a self-organizing process in which a long chain heteropolymer in a disorganized configuration spontaneously changes its shape to a highly organized structure in milliseconds. I explain how the energy and entropy landscape of protein chains is shaped to allow self-organization. I also show how these principles can be used in molecular level investigations of protein-protein interactions that lead to both beneficial dimerization or disastrous, disease producing and potentially fatal protein aggregation.
SLIDESHOW:
ics Colloquium
Friday, January 18, 2008
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, December 7, 2007
4:00 PM
Physics Building, Room 204
T. Egami [Host: Despina Louca]
University of Tennessee
"The Deep Puzzle of High-Temperature Superconductivity"
 
 Slideshow (PDF)
ABSTRACT:
It is already 21 years since high-temperature superconductivity (HTSC) in the cuprate was discovered by Müller and Bednorz. At the beginning many theoreticians, including several Nobel Laureates, claimed they knew the answer. Even today, they keep claiming so, while they acknowledge that they actually do not know how to solve the problem theoretically. In the mean time experimentalists succeeded in making impressive improvements of their capabilities, and we now know the remarkable details of the cuprates physics and the HTSC phenomena. What emerged from the vast amounts of experimental results is the realization that while the existing theories can describe parts of the observed phenomena, something fundamental appears to be lacking from the theory. The puzzle may be deeper than people prefer to admit. In my view one of the most fundamental problems is that the transition from the Mott-Hubbard insulator due to strong electron-electron interaction to the Fermi-liquid state is an abrupt one, while any mean-field approximation makes it falsely continuous. In this talk I discuss evidences from neutron scattering experiments that this transition involves nano-scale phase separation, reflecting the discontinuity in transition, and how this conflict could contribute to the HTSC phenomena.
SLIDESHOW:
ics Colloquium
Friday, November 30, 2007
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, November 16, 2007
4:00 PM
Physics Building, Room 204
Barry Dunning [Host: Tom Gallagher]
Rice University
"Designer atoms: Engineering Rydberg atom wavepackets using pulsed electric fields "
 
 Slideshow (PDF)
ABSTRACT:
Advances in experimental technique now allow application of pulsed unidirectional electric fields, termed half-cycle pulses (HCPs), to Rydberg atoms whose characteristic times are much less than the classical electron orbital period. In this limit each HCP simply delivers an impulsive momentum transfer or "kick" to the excited electron. A number of protocols for controlling and manipulating Rydberg atom wavepackets using carefully tailored sequences of HCPs will be described with emphasis on the production of quasi one-dimensional and near circular Rydberg states, on navigating electron wavepackets in phase space, and on studying reversible and irreversible dephasing using electric dipole echoes. Insights provided by this work into classical-quantum correspondence, physics in the ultra-fast ultra-intense regime, and decoherence in mesoscopic quantum systems will be discussed.
SLIDESHOW:
ics Colloquium
Friday, November 9, 2007
4:00 PM
Physics Building, Room 204
Gabriel Aeppli [Host: Seung-Hun Lee]
University College, London
"Entanglement in real magnets"
ABSTRACT:
Quantum entanglement is well-known to have consequences for optics and atomic physics, but is less recognized as impacting the properties of solids. Three examples - a dilute rare earth fluoride(Nature 425, 48), a transition metal oxide chain (Science 317, 1049), and a layered organometallic compound (PNAS 104, 15264), where entanglement matters for three real magnets are described.
ics Colloquium
Friday, November 2, 2007
4:00 PM
Physics Building, Room 204
Reinhard Schwienhorst [Host: Bob Hirosky ]
MSU
"Physics with top quarks"
 
 Slideshow (PDF)
ABSTRACT:
Experimental particle physics has reached a threshold that promises new and exciting insight into the fundamental structure of matter and the origin of particle masses in coming years. Due to its large mass, the top quark plays a key role in this quest for a deeper understanding of nature. We are currently learning a lot about the top quark through measurements at the Fermilab Tevatron. At the LHC at Cern, which starts in 2008, the top quark will become a probe for new physics and a tool for understanding mass generation. I will present our current understanding of the top quark and discuss its role in finding the new physics at the Tevatron and the LHC.
SLIDESHOW:
ics Colloquium
Friday, October 26, 2007
4:00 PM
Physics Building, Room 204
Aron Bernstein [Host: Dinko Pocanic]
Massachusetts Institute of Technology
"Measurement of the π 0 Lifetime: Probing the QCD Axial Anomaly"
 
 Slideshow (PDF)
ABSTRACT:
The π 0 lifetime has been measured with significantly improved accuracy at Jefferson Lab using the Primakoff effect. This was achieved by careful control of all of the experimental parameters and included auxiliary measurements of the Compton effect and pair production. This measurement is a test of a prediction based on the QCD axial anomaly plus few percent chiral corrections which are proportional to the mass difference of the up and down quarks. The basic physics, and a comparison of theory and experiment, will be presented in the context of spontaneous chiral symmetry breaking in QCD, some of its physical consequences, and other experimental tests.
SLIDESHOW:
ics Colloquium
Friday, October 19, 2007
4:00 PM
Physics Building, Room 204
David Hofman [Host: Bob Hirosky ]
University of Illinois Chicago
"Creating a Quark Gluon Plasma with Heavy Ion Collisions"
 
 Slideshow (PDF)
ABSTRACT:
It has now been seven years since a new era in relativistic heavy ion research began with the first beams at the Relativistic Heavy Ion Collider (RHIC). The primary goal of this effort was to heat a small volume of space so high that normal matter, comprised of protons and neutrons, dissolves into their constituent parts, the quarks and gluons, thus possibly creating a quark gluon plasma and perhaps even providing a window into how the universe may have looked in the first micro-seconds of its birth. In this talk, I will review the motivation and foundations for this endeavor, discuss several discoveries since RHIC began, explore a few of the more recent measurements, and look forward to what the very exciting and promising future will bring, especially in light of the startup of the new Large Hadron Collider in CERN.
SLIDESHOW:
ics Colloquium
Friday, October 12, 2007
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, October 5, 2007
4:00 PM
Physics Building, Room 204
Alex Meshik [Host: Keith Williams]
Washington University, St. Louis
"Natural Nuclear Reactor in Oklo"
ABSTRACT:
Natural nuclear reactors were probably abundant on Earth about 2 billion years ago, but so far only 17 have been found in Equatorial Africa, just a few miles apart from each other. We will talk about how these natural reactors were predicted, searched for and discovered, and how the major characteristics of these reactors have been determined. Then we will show how isotope analyses of fission xenon led to realization of the operational mode of natural reactors and understanding of why the reactors did not explode just after they reached criticality.Finally, we will consider some physical, environmental and geochemical implications of this fascinating natural phenomenon.
ics Colloquium
Friday, September 28, 2007
4:00 PM
Physics Building, Room 204
Sergey Kravchenko [Host: Joe Poon]
Northeastern University
"Interplay of disorder and interactions in two dimensions"
 
 Slideshow (PDF)
ABSTRACT:
The discovery of the metal-insulator transition (MIT) in two-dimensional electron systems challenged the veracity of one of the most influential conjectures in the physics of disordered electrons, which states that "in two dimensions, there are no true metals"; no matter how weak the disorder, electrons would be trapped and unable to conduct a current. However, that theory did not account for electron-electron interactions. Recently, we have investigated the interplay between interactions and disorder near the MIT using simultaneous measurements of electrical resistivity and magnetoconductance. It turns out that both the resistance and interaction amplitude exhibit a fan-like spread as the MIT is crossed. From these data we have constructed a resistance-interaction flow diagram of the MIT that clearly reveals a quantum critical point that separates the metallic state, stabilized by interactions, from the insulating state, where disorder prevails. The metallic side of this diagram is quantitatively described by the recent renormalization group theory (Punnoose and Finkelstein, Science 310, 289 (2005)) without any fitting parameters.
SLIDESHOW:
ics Colloquium
Friday, September 21, 2007
4:00 PM
Physics Building, Room 204
Ganapati Myneni [Host: Bellave Shivaram]
JLab
"JLab Scientific and Technological Advances with Commonwealth of Virginia Universities"
ABSTRACT:
The Continuous Electron Bean Accelerator Facility (CEBAF) at Jefferson Lab in Newport News was established by the Department of Energy as a result of the initiatives from the faculty of Physics at the University of Virginia. Initially the design called for room temperature copper accelerator structures. However, the first director of CEBAF chose Superconducting Radio Frequency (SRF) Technology for the acceleration of the high quality electron beams. This led to many world class scientific and technological advances at JLab including the core SRF and 2 K refrigeration systems. In this presentation I would like to narrate the development of single crystal large grain niobium technology for the benefit of SRF accelerator cavities including the Ganni 2 K refrigeration cycle for the efficient cooling of these accelerator structures. Further recent innovations and evolution of 10 - 50 MeV beam test facility, efficient design of cryomodules and compact THz sources are also discussed. In addition the plans of bringing all these scientific and technological advances for the benefit of the commonwealth of Virginia Universities under the umbrella of UVa are also explained.
ics Colloquium
Friday, September 14, 2007
4:00 PM
Physics Building, Room 204
Keith Williams [Host: Genya Kolomeisky]
University of Virginia
"A Century of Photo Physics: Mitchell Memorial Colloquium"
 
 Slideshow (PDF)
ABSTRACT:
The fascinating history of photography actually extends back more than one millennium, with pre-modern chemical photography finally catching hold around the 1820s through the pioneering work of Niépce and his subsequent collaboration with Daguerre. Viable silver emulsions were developed shortly thereafter by Talbot and others, but it was not until the 1880's that Eastman introduced prototype, flexible films familiar to modern photographers. At the turn of the last century, Eastman's silver halide films had already revolutionized the art world, opened new doors in optical spectroscopy, and established an entirely new mode of journalism. However, the underlying physical process itself was not understood until the late 1930s, when Mott and Gurney published their theory of latent image formation. Until that point, photographic capabilities were still severely limited because latent images were not stable, and emulsions were still quite slow. J.W. Mitchell established a more comprehensive theory of latent image formation that laid the foundation for improvement. His important contributions defined a turning point in modern film photography, and helped to bring high-performance emulsions to the market, where they have dominated for a half century and are still preferred by many professional photographers today. This talk will provide a visual review of the past century of photography, providing examples of daguerreotypes, cyanotypes, kalotypes, and modern silver halide photographs in the context of their role in science, art, and journalism. I will also present a brief survey of recent developments in digital image capture and discuss my expectations for advances in the near future. This memorial colloquium is given in recognition of the contributions J.W. Mitchell, emeritus Professor of Physics at UVa.
SLIDESHOW:
ics Colloquium
Friday, September 7, 2007
4:00 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, August 31, 2007
4:00 PM
Physics Building, Room 204
Moses Chan [Host: Jongsoo Yoon]
Penn State University
"Can a solid be “superfluid” ?"
 
 Slideshow (PDF)
ABSTRACT:
Abstract: At temperatures below 2.176K, liquid He-4 enters into a superfluid state and flows without any friction. The onset of superfluidity is associated with Bose-Einstein condensation where the He-4 atoms, which are bosons, condensed into a single momentum state and acquire quantum mechanical coherence over macroscopic distances. Recent torsional oscillator measurements of solid helium confined in porous media [1,2] and in bulk form [3,4] found evidence of non-classical rotational inertia indicating superfluid behavior below 0.2K. These measurements have been replicated in four other laboratories. Specific heat results will also be discussed. This work is done in collaboration with Eunseong Kim, Tony Clark, Xi Lin and Josh West and it is supported by the (U.S.) National Science Foundation.
SLIDESHOW:
ics Colloquium
Wednesday, April 25, 2007
3:30 PM
Physics Building, Room 204
Larry Yaffe [Host: Peter Arnold]
University of Washington
"Strongly-Coupled Plasmas and Gauge/String Duality"
 
 Slideshow (PDF)
ABSTRACT:
The quark-gluon plasma produced in relativistic heavy ion collisions has been found to behave like a low viscosity fluid whose properties are very different from those of a weakly interacting gas of quarks and gluons. It is an example of a strongly coupled, strongly correlated system, for which perturbative approximation techniques are not adequate. However, it is now understood that certain 3+1 dimensional gauge theories, similar to QCD, may be exactly reformulated as string theories in higher dimensions --- and this "gauge/string duality" is easiest to use in the strongly coupled limit of the gauge theory. Under this duality, properties of a high temperature, strongly coupled plasma are directly related to gravitational dynamics around 4+1 dimensional black holes. Using this duality, it is possible to compute, reliably, dynamical properties such as viscosity, energy loss of heavy particles, and emission spectra in certain strongly coupled gauge theory plasmas. This talk will describe this progress and discuss its applicability to the quark-gluon plasma produced in current and upcoming experiments.
SLIDESHOW:
ics Colloquium
Friday, April 20, 2007
4:00 PM
Physics Building, Room 204
Thomas Weinacht [Host: Bob Jones]
SUNY Stony Brook
"An Ultrafast Quantum Camera - Observing and Controlling Molecular Dynamics in Real Time"
 
 Slideshow (PDF)
ABSTRACT:
Ultrafast laser pulses allow us to 'take pictures' of atoms and molecules on their natural timescales (~10 -14 s). They can also be used to exert very strong and controlled forces, allowing us to direct the dynamics of the system they interact with. I will describe a series of experiments which aim to control and measure the wave function for a molecule as it dissociates. The ultimate aims of our efforts are to use shaped laser pulses as 'photonic reagents' and to make 'molecular movies', which depict the evolution of the molecular wave function as a function of time.
SLIDESHOW:
ics Colloquium
Friday, April 13, 2007
4:00 PM
Physics Building, Room 204
Dr Daniel Green [Host: Brad Cox]
Fermi National Accelerator Lab
"The CMS Experiment at the CERN Large Hadron Collider"
 
 Slideshow (PDF)
ABSTRACT:
The US is heavily involved in the Compact Muon Solenoid (CMS) experiment at the CERN Large Hadron Colllider (LHC). This new facility is explicitly designed to successfully search for the Higgs boson and generally to search for new symmetries of Nature such as Supersymmetry. The status of the LHC accelerator and the CMS experiment will be discussed as well as studies of the physics potential of CMS.
SLIDESHOW:
ics Colloquium
Friday, April 6, 2007
4:00 PM
Physics Building, Room 204
Haiyan Gao [Host: Simonetta Liuti]
Duke University
"A New Search on Neutron Electric Dipole Moment"
 
 Slideshow (PDF)
ABSTRACT:
A new experiment is being planned to search for the neutron Electric Dipole Moment (EDM) with an unprecedented sensitivity. The proposed search aims at a two orders of magnitude improvement over the current experimental limit. A search for a non-zero value of the neutron EDM is a direct search of the time reversal symmetry (T) violation. It provides a unique insight into CP violation because of the CPT theorem. The Standard Model (SM) prediction for the neutron EDM is below the current experimental limit by six orders of magnitude. However, many proposed models of electroweak interaction which are extensions beyond the SM predict much larger values of neutron EDM. The new experiment has the potential to reduce the acceptable range of predictions by two orders of magnitude. Furthermore, if new sources of CP violation are present in nature beyond the Standard Model and are relevant to hadronic systems, this experiment offers a unique opportunity to measure a non-zero value of neutron EDM. The current understanding of the baryogenesis suggests that other sources of CP violation might exist in nature beyond the Standard Model and beyond what have been observed so far. To explain the baryon number asymmetry in the universe through the grand unified theory or electroweak baryogenesis, substantial New Physics in the CP violation sector is required. In this talk, I will discuss this new experiment following a brief review of previous neutron EDM experiments.
SLIDESHOW:
ics Colloquium
Friday, March 30, 2007
4:00 PM
Physics Building, Room 204
Oleg Tchernyshyov [Host: Paul Fendley]
Johns Hopkins
"Topological defects in nanomagnets"
 
 Slideshow (PDF)
ABSTRACT:
The interplay of local and long-range forces in ferromagnets leads to the formation of mesoscopic domains with sharp boundaries (domain walls). The physics changes drastically when the magnet size becomes smaller than the width of a domain wall. In submicron magnets the magnetization forms intricate smooth patterns that involve the more exotic topological defects: integer and fractional vortices, skyrmions, merons, and magnetic monopoles. I will describe recent experiments with these entities and our attempts to describe their static and dynamic properties.
SLIDESHOW:
ics Colloquium
Friday, March 23, 2007
4:00 PM
Physics Building, Room 203
John Mather [Host: Brad Cox]
Goddard Space Flight Center
"From the Big Bang to the Nobel Prize and Beyond"
 
 Slideshow (PDF)
ABSTRACT:

The Cosmic Background Explorer (COBE) satellite, proposed in 1974 and launched by NASA in 1989, measured the cosmic microwave and infrared background radiation from the Big Bang and everything that happened later. The COBE team made three key measurements: the spectrum of the cosmic microwave background radiation (CMBR) matches a blackbody within 50 ppm (rms), the CMBR is anisotropic, with 10 ppm variations on a 7o angular scale, and the cosmic infrared background from previously unknown objects is as bright as all the known classes of galaxies. The first measurement confirmed the Hot Big Bang theory with unprecedented accuracy, the second is interpreted as representing quantum mechanical fluctuations in the primordial soup and the seeds of cosmic structure and the basis for the existence of galaxies, and the third is still not fully understood. I will describe the project history, the team members, the hardware and data processing, the major results, and their implications for science, and end with the outlook for future progress with new background measurements and large telescopes such as the James Webb Space Telescope. I will show recent progress on building the JWST, with illustrations of the key technologies.

SLIDESHOW:
ics Colloquium
Friday, March 16, 2007
4:00 PM
Physics Building, Room 204
David Weiss [Host: Tom Gallagher]
Penn State University
"Quantum simulations and quantum computation with atoms in optical lattices"
ABSTRACT:
I will review the physics of 1D Bose gases, show how we experimentally implement them, and describe experiments that confirm the longstanding exact theory across all coupling regimes. I will also describe quantum Newton's cradles, which are out of equilibrium 1D gases that act unlike any other many-body system. Finally, I will show how we image 3D arrays of hundreds of single atoms, an important step on the way to making a neutral atom quantum computer.
ics Colloquium
Friday, March 2, 2007
4:00 PM
Physics Building, Room 204
Avik Ghosh [Host: Keith Williams]
University of Virginia
"The physics of nanoelectronic devices"
 
 Slideshow (PDF)
ABSTRACT:
Nanoscale conductors, such as ultrasmall molecular wires, allow us to test our understanding of fundamental non-equilibrium transport physics, as well as explore new device possibilities. I will start with a generic treatment of current flow through a single energy level, and then generalize to include realistic bandstructure models and a full quantum kinetic theory of current flow. This allows us to interpolate between semi-empirical models that provide quick physical insights, and ‘first-principles’ models with no adjustable parameters. Using this formalism, we can quantitatively explain various experimental features and fundamental performance limits of molecular electronics. In the above treatments, we treat electrons as weakly interacting, operating in the ‘mean field limit’. However, ultra-short molecules are unique in that they often possess large electronic and vibronic correlation energies with prominent experimental signatures. Strong correlation requires a completely different transport approach in the molecular many-body Fock space that accounts for non-perturbative interactions. I will show that many features such as negative differential resistance, Coulomb Blockade, hysteretic switching and random-telegraph noise can be understood in terms of the dynamics of such many-body levels and their state filling under bias. A lot of the applications of nanoelectronics could involve bridging the mean-field and strongly correlated regimes, where the theory becomes particularly challenging. For instance, the tunable quantum coupling of current flow in present day silicon transistors with engineered molecular adsorbates could lead to devices operating on completely novel principles.
SLIDESHOW:
ics Colloquium
Friday, February 16, 2007
4:00 PM
Physics Building, Room 204
Carlos Sa de Melo [Host: Joe Poon]
Georgia Tech
"The Evolution from BCS to Bose-Einstein Condensation: Superfluidity in Metals, Neutrons Stars, Nuclei, and Ultra-Cold Atoms"
ABSTRACT:
> Superfluidity is a very interesting phenomenon that has been found in metals, > neutron stars, nuclei and more recently in ultra-cold atoms. For a given > metal, neutron star, or nuclei there is essentially "zero" tunability of the > particle density or interaction strength, and thus superfluid properties can > not be controlled at the turn of a knob. However, in ultra-cold Fermi atoms > the interaction strength and the particle density can be tuned to change > qualitatively and quantitatively superfluid properties. This tunability allows > for the study of the evolution from BCS (weak coupling) superfluidity of large > Cooper pairs to Bose-Einstein condensation (strong coupling) superfluidity of > tightly bound molecules. I will discuss the BCS to BEC evolution in s-wave > and p-wave angular momentum channels, and will conclude that this evolution is just a crossover phenomenon for s-wave, while a quantum phase transition takes place for the p-wave case.
ics Colloquium
Friday, February 9, 2007
4:00 PM
Physics Building, Room 204
Keith Williams [Host: Dinko Pocanic]
University of Virginia
"Molecular Electronics- Past, Present and Future"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Friday, February 2, 2007
4:00 PM
Physics Building, Room 204
Sang-Wook Cheong [Host: Seunghun Lee]
Rutgers University
"New magnetic twists for multiferroicity"
ics Colloquium
Friday, January 19, 2007
4:00 PM
Physics Building, Room 204
Dan Kaplan [Host: E. Craig Dukes]
Illinois Institute of Technology
"New Ideas in Neutrino Physics"
 
 Slideshow (PDF)
ABSTRACT:
The existence of neutrinos -- neutral, massless, almost- noninteracting counterparts of the electron -- was first proposed in 1930, in response to apparently incomprehensible experimental results. Neutrinos have been a puzzle ever since! One indicator of their importance is the unusually large number of Nobel prizes awarded for neutrino work, the most recent in 2002. A brief account of the neutrino story will lead to a discussion of current issues in neutrino physics, including the intriguing possibility that neutrino interactions explain the existence of all matter in the universe. Techniques for the future study of neutrino physics will be described.
SLIDESHOW:
ics Colloquium
Friday, November 24, 2006
4:00 PM
Physics Building, Room 204
Thanksgiving Recess [Host: N/A]
N/A
"N/A"
ics Colloquium
Friday, November 17, 2006
4:00 PM
Physics Building, Room 204
Csaba Csaki [Host: P.Q. Hung]
Cornell University
"Searching for the mechanism of electroweak symmetry breaking"
 
 Slideshow (PDF)
ABSTRACT:
The standard model of particle physics has been very successful at explaining all collider experiments to date. However, it does not give a well-motivated explanation for why the electroweak symmetry should be spontaneously broken. Recently several new possible theories have been suggested to cure this shortcoming. I describe the motivations and the consequences of some of these new theories, including large and warped extra dimensions, higgsless and little higgs models.
SLIDESHOW:
ics Colloquium
Friday, November 3, 2006
4:00 PM
Physics Building, Room 204
Vladimir Kresin [Host: Stu Wolf]
LBL
"Potential Room Temperature Superconductivity in Metallic Nanoclusters"
 
 Slideshow (PDF)
ABSTRACT:
Superconductivity is a peculiar state of matter which is manifested in such diverse fields as solid state physics, nuclear physics, astrophysics, biology, etc. In this talk we focus on small metallic nanoclusters (N 102-103 where N is the number of free carriers) which contain delocalized electrons. These electrons form shells similar to those in atoms or nuclei. It turns out that under special, but perfectly realistic conditions, superconducting pairing is very strong and can lead to high values of Tc. We have shown that for realistic sets of parameters one can observe very high values of Tc (Tc 102 K ) as well as a strong modification of the energy spectrum. Nanoclusters should form a new family of high temperature superconductors and in principle, it should be possible to raise Tc up to room temperature. We have proposed specific experiments aimed at detecting this phenomenon (e.g. spectroscopy and magnetic properties). This phenomenon is quite promising for the creation of high Tc superconducting tunneling networks.
SLIDESHOW:
ics Colloquium
Friday, October 27, 2006
4:00 PM
Physics Building, Room 204
Luis Orozco [Host: Olivier Pfister]
University of Maryland
"Conditional measurements in cavity QED"
 
 Slideshow (PDF)
ABSTRACT:
One of the striking differences between the classical world and the quantum world is the measurement process. This opens interesting possibilities to study how a quantum system evolves after a measurement. We have implemented a cavity QED system, where an atom or a few atoms interact with a single mode of the electromagnetic field. This interaction is such that a quantum fluctuation, the emission of a single photon, is a large event. We are studying, by conditional measurements, the dynamics of the cavity QED system as it returns to steady state after a fluctuation and can now relate this to some of its intrinsic properties such as entanglement.
SLIDESHOW:
ics Colloquium
Tuesday, October 24, 2006
3:30 PM
Physics Building, Room 204
Seunghun Lee [Host: Dinko Pocanic]
University of Virginia
"Almost everything that you'd like to know about frustrated magnets"
ics Colloquium
Monday, October 23, 2006
3:30 PM
Physics Building, Room 204
Jongsoo Yoon [Host: Dinko Pocanic]
University of Virginia
"Magnetically induced electronic states in two-dimensional superconductors"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Friday, October 20, 2006
4:00 PM
Physics Building, Room 204
Peter Arnold [Host: Dinko Pocanic]
University of Virginia
"The Plasma Physics of Quark-Gluon Plasma (a theorist's perspective)"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Tuesday, October 17, 2006
3:30 PM
Physics Building, Room 204
Nilanga Liyange [Host: Dinko Pocanic]
University of Virgina
"Jefferson Lab Hall: A neutron spin structure program"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Monday, October 16, 2006
3:30 PM
Physics Building, Room 204
Cass Sackett [Host: Dinko Pocanic]
University of Virginia
"An Atom Interferometer Using Bose-Einstein"
 
 Slideshow (PDF)
SLIDESHOW:
ics Colloquium
Friday, October 13, 2006
4:00 PM
Physics Building, Room 204
Bill Phillips [Host: Thomas Gallagher]
NIST
""A Bose Condensate in an Optical Lattice: cold atoms meet solid state""
ABSTRACT:
An atomic-gas Bose-Einstein Condensate, placed in the periodic light-shift potential of an optical standing wave, exhibits many features that are similar to the familiar problem of electrons moving in the periodic potential of a solid-state crystal lattice. Among the differences are that the BEC represents a wavefunction whose coherence extends over the entire lattice, with what is essentially a single quasi momentum and that the lattice potential can be turned on and off or accelerated through space. Experiments that are not easily done with solids are often straightforward with optical lattices, sometimes with surprising results.
ics Colloquium
Friday, October 6, 2006
4:00 PM
Physics Building, Room 204
Howard Carmichael [Host: Olivier Pfister]
University of Auckland, New Zealand
"Nonclassical Light and Glauber's Theory of Optical Coherence"
 
 Slideshow (PDF)
ABSTRACT:
The year 2005 celebrated the seminal contributions of Albert Einstein to physics, including his treatment of the photoelectric effect and his introduction of the quantum of light. The same year saw Roy Glauber awarded the Nobel Prize in Physics -- ``for his contribution to the quantum theory of optical coherence''. My talk will explore the connections between Glauber's and Einstein's work, while at the same time posing the question...in what sense, exactly, does light act as a particle and not a wave?
SLIDESHOW:
ics Colloquium
Friday, September 29, 2006
4:00 PM
Physics Building, Room 204
Randy Ruchti [Host: Brad Cox]
Notre Dame University and NSF
"The National Science Foundation, One Particle Physicist's Experience"
 
 Slideshow (PDF)
ABSTRACT:
During a recent term of service on the High Energy Physics Advisory Panel (HEPAP), which jointly advises DOE and NSF on particle physics matters, the speaker was persuaded of the importance of direct participation by active research scientists in the process of federal funding for research and education programs. This view has motivated a temporary term of service by the speaker at the National Science Foundation. The presentation will provide a view of how the NSF conducts its business in Elementary Particle Physics, from the perspective of an university-based experimentalist and faculty member serving as a visiting program officer.
SLIDESHOW:
ics Colloquium
Friday, September 22, 2006
4:00 PM
Physics Building, Room 204
Paul Fendley [Host: Genya Kolomeisky]
University of Virginia
"Topological Quantum Computation"
ics Colloquium
Friday, September 15, 2006
4:00 PM
Physics Building, Room 204
Brooks Harris [Host: Seunghun Lee]
University of Pennsylvania
"The Unusual Symmetry of Ferroelectricity in Incommensurate Magnets"
ABSTRACT:
The coupling between electric and magnetic properties in condensed matter systems is usually very weak. In part this may be viewed as being a result of the fact that the electric and magnetic fields exhibit different symmetries which do not naturally couple to one another. Here I discuss a class of materials which display a very unusual phase transition in which magnetic ordering and the development of ferroelectricity occur simultaneously. This coupling has drawn great interest recently mainly due to various experimental results for this fascinating coupling whereby magnetic ordering induces erroelectricity. My main objective is to understand the phenomonology of this magnetoelectric coupling via a Landau expansion whose consequences depend crucially on the symmetry properties of the magnetic order and the consistency of this order with ferroelectric ordering. Even this simple phenomenological theory explains a number of nontrivial ferroelectric properties which have been observed. I discuss briefly the advantages of such a symmetry analysis versus specific microscopic models.
ics Colloquium
Friday, September 8, 2006
4:00 PM
Physics Building, Room 204
Vittorio Celli [Host: Steve Thornton]
University of Virginia
"The Ocean Tides: Myth and Truth from Galileo to GPS"
ABSTRACT:
It is widely believed, and taught in Physics courses, that two high tides of equal magnitude occur daily. In reality, the tides are a complicated sloshing of the oceans with three main periods: M2 (12.82h) due to the Moon, S2 (12h) due to the Sun, and K1 (23.93h) due to both and to the tilt of the Earth's axis. Following Newton, one can compute the magnitude of the tidal forces, but an understanding of tide dynamics, based on the work of Laplace and Lord Kelvin, is incomplete even today. Over most coastlines M2 is dominant, but in New Orleans, for instance, there is only one high tide each day. In the North Atlantic, the M2 tide runs up the European coast and down the American coast, circling a mid-Ocean point of zero amplitude. This "amphidromic" behavior is seen in many basins, and is due to the Coriolis force acting on tidal currents. Thus, the ocean tides are a direct proof of the Earth's rotation, as Galileo maintained. In fact, his kinematic theory of the "ebb and flow of the waters", based on the Copernican motions of Earth, Sun and Moon, is basically correct, although incomplete. An accurate global picture of tidal amplitudes (but not yet of tidal currents) has been obtained by GPS satellites, and is in turn relevant to space age science and technology.
ics Special Colloquium
Tuesday, May 9, 2006
3:30 PM
Physics Building, Room 204
Daniela C. Rohe [Host: Nilanga Liyanage]
University of Basel, Switzerland
"Experiments With Polarized 3He at the Mainz Microtron (MAMI)"
ABSTRACT:
Polarized 3He is an interesting target for nuclear physics experiments due to its particular spin structure which allows its use as a polarized neutron as well as polarized proton target. Further, the nucleus is simple enough that exact solutions of its wave function and the reaction channels are available. On the other hand all important interactions between the three nucleons are present and can be studied. Polarization experiments open up new degrees of freedom and find a wide field of application due to their particular sensitivity as well as due to the advantages of asymmetry measurements in general.

In this talk I will discuss polarized target technology and will explain the technique and installation used to polarize 3He for the nuclear physics target at MAMI. The emphasis of the talk is on the results achieved so far at MAMI with polarized 3He. Their purpose is twofold: To test the reliability of the theoretical description of 3He and to measure the electric form factor of the neutron. An outlook about ongoing and future research will be given.

ics Special Colloquium
Thursday, May 4, 2006
3:00 PM
Physics Building, Room 205
Xiaochao Zheng [Host: Nilanga Liyanage]
MIT
"What Have We Learned from Polarized Deep Inelastic Scattering?"
ABSTRACT:
Since the 1980's development in polarized electron sources and polarized target techniques has brought the experimental study of the nucleon into a new era: The spin structure of the nucleon has been explored with polarized electron scattering. Now twenty years have passed. What have we learned from the data? Do they agree with predictions from quantum chromo-dynamics (QCD), the theory for strong interactions? And what about predictions from constituent quark models?

I will start from an introduction to the study of hadron structure using lepton deep inelastic scattering and give an overview of world data and what we have already learned about nucleon structure. Then I will present results from a precision experiment completed at Jefferson Lab on the neutron spin in the valence quark region, and discuss about the future of this measurement.

The last 10 minutes of the talk will be devoted to a different topic: using polarized electron scattering to test the electro-weak Standard Model and hadronic structure, and introducing the PV-DIS program that is being just launched at Jefferson Lab.

The talk will be given on an non-expert level.

ics Special Colloquium
Monday, May 1, 2006
3:30 PM
Physics Building, Room 204
Kent Paschke [Host: Nilanga Liyanage]
University of Massachusetts
"Using Parity Violation to Probe Strange Quarks in the Nucleon"
ABSTRACT:
The basic nuclear building block of our day-to-day world, the nucleon, is well described in terms of quarks of only two varieties: the up and down quarks. However, the nucleon is more complex than the apparent success of the constituent quark model would imply. One example of this complexity is the possible role of the strange quark in the nucleon. Precision measurements of parity violation in electron scattering, a symmetry violation which is forbidden under the electromagnetic interaction but allowed by the weak force, can be used to disentangle the contributions of strange quarks from other components of the nucleon electric and magnetic structure. I will report new results on the most precise measurement to date of parity-violation in electron-nucleon scattering, from the HAPPEX collaboration at Thomas Jefferson National Accelerator Facility, and discuss implications for the question of strange quarks in the nucleon.
ics Colloquium
Friday, April 28, 2006
4:00 PM
Physics Building, Room 204
Paul C. Canfield [Host: Seung-Hun Lee]
Ames Laboratory and Department of Physics and Astronomy, Iowa State University
"The Design, Growth, Discovery and Characterization of Novel Intermetallic Compounds"
ABSTRACT:
In this talk I will review the motivations as well as means for the design, growth or search for novel materials. I will provide examples of what physics you can peruse ranging from superconductivity in MgB2, to the spin-glass state in rare earth based quasicrystals, to field induced quantum criticality in Yb-based intermetallics. The emphasis will be on the joy of, and tools for, discovery.
ics Special Colloquium
Tuesday, April 25, 2006
3:30 PM
Physics Building, Room 204
Xiaodong Jiang [Host: Nilanga Liyanage]
Rutgers University
"Can Quarks in a Polarized Nucleon Tell Left from Right ?"
ABSTRACT:
In the strong interaction, which follows the parity-conserving theory of Quantum Chromodynamics (QCD), can quarks in a polarized nucleon manage to tell left from right ? For "collinear quarks" in a longitudinally polarized nucleon, the answer is simply NO. However, when a nucleon's spin is oriented transverse to it's momentum, quarks inside can figure out left from right through their transverse spin distributions (transversity) and through their angular motions. Recent spin physics experiments from HERMES at DESY and COMPASS at CERN have revealed such an amazing behavior of quarks for the first time, left us with even more questions. Two upcoming Jefferson Lab experiments are designed to provide more answers as to how exactly u- and d-quarks tell left from right in a transversely polarized nucleon.
ics Colloquium
Friday, April 21, 2006
4:00 PM
Physics Building, Room 204
Peter Shanahan [Host: Brad Cox]
Fermi National Accelerator Laboratory
"Recent Results and Future Prospects in Neutrino Physics"
ABSTRACT:
More than 40 years ago, a Nobel Prize winning experiment showed that neutrinos come in distinct flavors: neutrinos created in association with muons produced only muons when they interacted, and not electrons. Over the past decade, however, a series of experiments have established that the flavor of a neutrino does indeed change with time. The most likely explanation of this phenomenon is neutrino flavor oscillation, requiring a finite neutrino mass and therefore an extension of the Standard Model of Particle Physics. Related physics at energies far beyond direct experimental reach may well explain the preponderance of matter over antimatter in the universe. The impact of accelerator-based experiments in our understanding of neutrino masses and flavor will be discussed, with an emphasis on current and anticipated experiments at Fermilab.
ics Colloquium
Friday, April 14, 2006
4:00 PM
Physics Building, Room 204
Yuri Gershtein [Host: Bob Hirosky]
Florida State University
"News from the Energy Frontier"
ABSTRACT:
It is exciting time for particle physics. Currently, Fermilab's Tevatron, the highest energy accelerator, delivered more than 1 fb-1 to the experiments (CDF and DZero). In just over a year, the Large Hadron Collider (LHC) at CERN will turn on, moving the energy frontier by almost an order of magnitude - an event the likes of which we did not see in almost three decades. I will talk about the fundamental questions that are addressed by doing physics at the energy frontier, present some new results from DZero experiment and describe the status and prospects of the CMS detector at the LHC.
ics Colloquium
Friday, April 7, 2006
4:00 PM
Physics Building, Room 204
Oscar Rondon-Aramayo [Host: Genya Kolomeisky]
UVA
"Nucleon Structure Studies with Polarized Photons and Polarized Nucleons"
ABSTRACT:
The quark and gluon structure of the nucleons (protons and neutrons) was established by illuminating atomic nuclei with high energy unpolarized real and virtual photons. The interactions between quarks follow "scaling" rules that were also established with unpolarized photons. With polarized photons it is possible to explore the nucleon structure even further. Polarized photons have been used to determine that quarks carry only 1/3 of the spin, but the distribution of spin among types ("flavors") of quarks is still under study. And the "missing" spin carriers are still being investigated. The interactions between quarks and gluons have barely been explored experimentally. Polarized photons can also uncover the details of those interactions and relate them to calculations based on Quantum Chromodynamics - QCD, the fundamental theory of strong interactions. There is an extensive program of nucleon structure studies with polarized photons and polarized nuclear targets at Jefferson Lab with the goal of answering some of these and other related questions. Highlights of the Hall C component of this program will be presented.
ics Colloquium
Friday, March 31, 2006
4:00 PM
Physics Building, Room 204
Tom Ferbel [Host: Bob Hirosky]
DOE/University of Rochester
"Whither Particle Physics"
ics Colloquium
Friday, March 24, 2006
4:00 PM
Physics Building, Room 204
Sally Dawson [Host: P.Q. Hung]
Brookhaven National Laboratory
"Adventures at the Terascale"
ABSTRACT:
Exciting opportunities are in store for particle physics over the coming decade, with new tools and experiments poised to explore the frontiers of high energy, the smallest distance scales, and processes of great rarity. Einstein's dream of a unification of all forces will be tested at new energy scales and with greater precision than ever before. The Large Hadron Collider at CERN will begin the exploration of higher energy scales than have been tested previously and a possible future high energy lepton collider will continue our explorations.
ics Colloquium
Friday, March 17, 2006
4:00 PM
Physics Building, Room 204
Ralph McNutt [Host: Blaine Norum]
Johns Hopkins University
"The MESSENGER Mission to Mercury: Science and Status"
ics Colloquium
Thursday, March 16, 2006
4:00 PM
Physics Building, Room 204
David Weiss [Host: Tom Gallagher]
Penn State University
ics Colloquium
Friday, March 10, 2006
4:00 PM
Physics Building, Room 204
****SPRING RECESS*****
ics Colloquium
Friday, March 3, 2006
4:00 PM
Physics Building, Room 204
RESERVED [Host: JKG]
UVA
"TBA"
ics Colloquium
Friday, February 24, 2006
4:00 PM
Physics Building, Room 204
Linda Horton [Host: Despina Louca]
ORNL
"The Center for Nanophase Materials Sciences"
ABSTRACT:
The Center for Nanophase Materials Sciences is the newest user facility at Oak Ridge National Laboratory. Located adjacent to the Spallation Neutron Source, the CNMS is one of 5 nanoscience user facilities being built by the Department of Energy. CNMS is open to scientists and engineers for research to understand the phenomena that control the properties of nanoscale materials. CNMS emphasizes synthesis and characterization, including neutron scattering and electron microscopy. One important capability is a 10,000 sq ft nanofabrication clean room facility. CNMS will also integrate theory and modeling with the experimental program, a critical aspect of the research. The presentation will discuss the capabilities of the new facility, the scientific program, and opportunities for research and collaboration.
ics Joint Astronomy-Physics Colloquium
Friday, February 17, 2006
4:00 PM
Physics Building, Room 203
Christopher Stubbs [Host: Brad Cox]
Harvard University
"Preliminary Results on the Nature of the Dark Energy from the ESSENCE Supernova Survey "
ABSTRACT:
The discovery of the accelerating expansion of the Universe provides clear evidence of physics beyond the standard model. Our current challenge is figuring out what it means! I will describe the initial results we have obtained in the ESSENCE supernova survey. This project was designed to detect 200 type Ia supernovae in the redshift range between 0.2 < z < 0.8, with the goal of measuring the equation of state parameter of the Dark Energy. We are paying particular attention to potential sources of systematic errors that might afflict the measurement, and I will describe some of the steps we are taking to both control and quantify these effects.
ics Colloquium
Friday, February 3, 2006
4:00 PM
Physics Building, Room 204
Gail McLaughlin [Host: Steve Thornton]
North Carolina State University
"Exploding Stars, Neutrinos, and Nucleosynthesis"
ABSTRACT:
The subject of supernovae is a unique combination of many different branches of physics and there are different ways in which we can probe the inner workings of these objects. Beyond examining light curves from the explosion, one can study nucleosynthesis products and neutrino spectra. The discovery of a whole new type of supernova, one which creates a gamma ray burst, has created a new frontier in research on neutrinos and element synthesis. I will discuss the role neutrinos play in determining whether the heaviest elements, such as uranium and thorium, are produced in these environments.
ics Colloquium
Friday, January 20, 2006
4:00 PM
Physics Building, Room 204
Art Brill [Host: Genya Kolomeisky]
UVA
"Nuclear Spin-Electron Spin Interactions in the Three-Atom System H2N"
ABSTRACT:
H2N has one unpaired electron and three nuclei of non-zero spin. The four H2N isotopes from 1H, 2H, 14N and 15N have corresponding sets of hyperfine interactions. Measurements of these constrain calculations of electronic wavefunctions and energies, and provide basic knowledge for application to more complex systems. Nuclear spin-state mixing arises from the off-diagonal elements of the nuclear energy matrix, e.g. Mxx ≡ σκ 〈ψ|Σ (Skzx2kn/r5kn + Sk'zx2k'n/r5k'n|Ψ〉 (Airne and Brill, Phys. Rev.A 63 052511). The principle hyperfine A-values can be expressed in terms of the M’s, e.g. Azz = AFermi - (4/3σ)( Mxx + Myy - 2 Mzz), thereby simplifying the energy matrices. In the absence of nuclear spin-state mixing (i.e. each state pure mI) there are, e.g. 10 epr transitions in D215N and 15 in D214N, all ΔmI = 0 fully allowed. In the presence of mixing there are 243 in D215N and 729 in D214N, with large differences in probability among transitions. Because of numerous, at least partially allowed, overlapping transitions, useful information can be obscured in H2N magnetic resonance spectra. Research is required to arrive at effective experimental conditions. The wide range of transition probabilities will cause H2N resonances to exhibit a corresponding range of microwave power saturation behavior. Simulations display remarkable effects which call for experimental verification by employing a wide range of powers. The nuclear Zeeman interaction (proportional to B) perturbs both the energy and state mixing of nuclear levels, thereby affecting the separation and probability of resonances. Of special interest are the fields Bcross at which pairs of hyperfine levels draw closest. A spectrometer with microwave frequency scanning at fixed B would be useful for centers like H2N in which on-diagonal hyperfine energy matrix elements depend significantly upon B.
ics Colloquium
Friday, December 2, 2005
4:00 PM
Physics Building, Room 204
Roger Rusach [Host: Brad Cox]
University of Minnesota
"Physics and the CMS Detector at the CERN Large Hadron Collider"
ABSTRACT:
In 2007 a new proton-proton collider, the LHC, will turn on and a whole new energy domain will become accessible to experiment. Indications of what we might observe come from current measurements in experiments in high-energy physics, astrophysics and cosmology. We will discuss what problems in physics might be resolved with data from the LHC, describe how the detectors work and what are the special challenges associated with building a detector of the scale required for this energy region.
ics Colloquium
Friday, November 25, 2005
4:00 PM
Physics Building, Room 204
****THANKSGIVING BREAK****
ics Colloquium
Friday, November 18, 2005
4:00 PM
Physics Building, Room 204
Joe Poon [Host: Genya Kolomeisky]
UVA
"Glassy Metals – Complexity Made Simpler "
ABSTRACT:
Although ubiquitous in nature and technology, the microscopic study of liquids and glasses lags far behind that of crystals and quasicrystals. This is because liquids and glasses do not exhibit long-range order, which frustrates theoretical description. To date, the common approaches for modeling the dynamics and glass transition of liquids are based on the potential energy landscape paradigm. Theoretical approaches such as the mode-coupling theory and replica method, although successful in advancing our understanding of the dynamics and thermodynamics of the liquid-glass transition, have not provided specific predictions of the important parameters of the glassy state. Recently, a simple complementary model based on atomic-level fluctuations in the amorphous network has been successfully applied to the computation of these parameters. The latter approach may also provide a pathway to a more general microscopic understanding of liquids and glasses. The rest of this talk will focus on glassy metals as futuristic metals with certain promising and enabling properties.
ics Colloquium
Friday, November 11, 2005
4:00 PM
Physics Building, Room 204
Jeremy Levy [Host: Joe Poon]
University of Pittsburgh
"Oxide-Semiconductor Materials for Quantum Computation"
ABSTRACT:
Quantum computers, as yet undeveloped, are believed to be able to efficiently solve strategically important problems like number factorization, database search, and the Schrodinger equation itself. The staggering potential of these and other applications has led to a worldwide race to build the first working quantum computer. The state of experimental quantum computation is primitive--neither quantum bits (qubits) nor quantum gates (qugates) have been demonstrated in a scalable form. In this talk, I will give an overview of the new field of quantum information science and technology, and will describe a proposal to create a quantum information processor using ferroelectrically coupled electron spins in silicon. This approach combines the latest advances in nanostructure and heterostructure design, ultrafast optical control, measurement science and signal processing. Progress toward these goals, pursued within the Center for Oxide-Semiconductor Materials for Quantum Computation (COSMQC), will be described. This work is supported by DARPA QuIST through ARO contract number DAAD-19-01-1-0650.
ics Colloquium
Friday, November 4, 2005
4:00 PM
Physics Building, Room 204
Peter Olson [Host: Keith Williams]
John Hopkins University - Earth and Planetary Sciences
"Probing the Geodynamo"
ics Colloquium
Friday, October 28, 2005
4:00 PM
Physics Building, Room 204
Catherine Brechnigac [Host: Thomas Gallagher]
"Clusters: a route to study stability at nanometer scale"
ics Colloquium
Friday, October 21, 2005
4:00 PM
Physics Building, Room 204
Gary Goldstein [Host: Simonetta Liuti ]
Tufts University
"The Importance of Spin in Particle Physics"
ics Colloquium
Friday, October 7, 2005
4:00 PM
Physics Building, Room 204
Sarah Eno [Host: Bob Hirosky]
University of Maryland
"The CMS Experiment"
ics This will be a joint Math/Physics/History colloquium.
Friday, September 30, 2005
4:00 PM
Physics Building, Room 203
Mordechai Feingold [Host: Michael Fowler]
Caltech
"All Was Light: Isaac Newton's Revolutions"
ics Colloquium
Friday, September 23, 2005
4:00 PM
Physics Building, Room 204
William Klemperer [Host: Thomas Gallagher]
Harvard University
"The Chemistry of the Universe"
ics Colloquium
Friday, September 16, 2005
4:00 PM
Physics Building, Room 204
Chris Morris [Host: Craig Dukes]
Los Alamos National Laboratory
"Charge Particle Radiography for National Security"
ABSTRACT:
Intermediate energy protons are being used for very fast (flash) radiography. Proton beams have shown to provide a flexible time format, excellent position resolution, and adjustable contrast, for a wide range of high explosive driven experiments. These experiments are playing an increasingly important role in the nuclear stockpile stewardship program. An outgrowth of this work has been the development of cosmic ray radiography for cargo and vehicle inspection. An overview of charge particle radiography and its uses for national security applications will be presented.
ics Colloquium
Friday, September 9, 2005
4:00 PM
Physics Building, Room 203
Doug Osheroff [Host: Craig Dukes]
Stanford University
"Understanding The Columbia Shuttle Accident and NASA's Challenges Posed by Discovery"
ABSTRACT:
On 1 February 2003 space shuttle Columbia broke up during re-entry over the plains of East Texas. The speaker was a member of the board appointed to investigate that disaster. It was ultimately found that the physical cause of the accident was a piece of thermally insulating foam that struck the leading edge of the left wing during launch. This foam had a density of just 1/30th the density of water, yet it created a hole estimated to be approximately 25 cm square, which allowed superheated gases to enter the wing on re-entry, consuming the interior of the wing in a matter of a few minutes. The final report showed that NASA had that such foam strikes had occurred before, but continued to fly in the face of clear and persistent danger. The speaker will also discus the organizational aspects of this accident, many of which are common to all large organizations, and the future of the program in light of Discovery's foam shedding.
ics Colloquium
Thursday, September 8, 2005
4:00 PM
Physics Building, Room 204
Thom Mason [Host: Seunghun Lee]
Director, Spallation Neutron Source - Oak Ridge National Laboratory
"The Spallation Neutron Source: A Powerful Tool for Materials Research"
ABSTRACT:
The wavelengths and energies of thermal and cold neutrons are ideally matched to the length and energy scales in the materials that underpin technologies of the present and future: ranging from semiconductors to magnetic devices, composites to biomaterials and polymers. The Spallation Neutron Source will use an accelerator to produce the most intense beams of neutrons in the world when it is complete in 2006. The project is being built by a collaboration of six U.S. Department of Energy laboratories. It will serve a diverse community of users drawn from academia, industry, and government labs with interests in condensed matter physics, chemistry, engineering materials, biology, and beyond.
ics Colloquium
Friday, September 2, 2005
4:00 PM
Physics Building, Room 204
AVAILABLE
ics Colloquium
Friday, August 26, 2005
4:00 PM
Physics Building, Room 204
AVAILABLE
ics Special Colloquium
 [Coffee will be served in Room 205 at 3:30 PM]
Tuesday, May 31, 2005
4:00 PM
Physics Building, Room 204
Professor Theodor Hansch [Host: Thomas Gallagher]
Max Planck Institute for Quantum Optics
"Towards a Quantum Laboratory on a Chip"
ics Colloquium
Friday, May 6, 2005
4:00 PM
Physics Building, Room 204
Sankar Das Sarma [Host: Keith Williams]
University of MarylandCondensed Matter Theory Center -
"Tidbits About Qubits: Spin Computation in Nanostructures"
ABSTRACT:
I will provide an introduction to the emerging field of spintronics and spin qubits in this talk. Active control of carrier spin in nanostructures of semiconductors and other electronic materials is projected to lead to new device functionalities in the future. In particular, it may be possible to envision memory and logic operations being carried out on the same 'spintronic' chip. I will discuss various aspects of fundamental physics related to this new research area of spin electronics with the particular emphasis on localized electron spins in semiconductor nanostructures, such as GaAs quantum dots and P donors in Si. A revolutionary possibility in the (perhaps, far) future is using the natural two-level quantum dynamics of electron spin to create robust quantum bits ('qubits') which could be used to carry out solid state quantum information processing or quantum computation. I will discuss in details the questions of entanglement, decoherence, quantum error correction, and quantum gates in semiconductor nanostructure-based solid state spin quantum computer architectures, critically discussing from a theoretical perspective the current status of the field and the prospects for carrying out large-scale quantum computation using solid state spin qubits. Aspects of fundamental spin physics in the solid state environment will be emphasized in this talk. This research has been supported by LPS, ARDA, NSA, ARO, DARPA, ONR, and Please see http://www.physics.umd.edu/cmtc for the relevant publications.
ics Colloquium
Friday, April 29, 2005
4:00 PM
Physics Building, Room 204
Marina Artuso [Host: Brad Cox]
Syracuse
"In Search of New Physics: The Clues From Charm"
ABSTRACT:
The study of the interactions between the fundamental building blocks of matter is a critical component of our understanding of the history of the universe and its dynamics. My talk will describe how our experimental study of charm quark decays may test key features of our present understanding of these interactions, and, possibly, open a window towards new physics. The experimental data discussed are taken at the CESR electron-positron collider.
ics Colloquium
Friday, April 22, 2005
4:00 PM
Physics Building, Room 204
Klaus Hon [Host: Brad Cox]
Ohio State University
"The Asymmetry Between Matter and Anti Matter - or -How to Know if it is Safe to Shake an Alien's Hand?"
ABSTRACT:
Most of us have looked at the spectacular pictures taken by the Hubble Space Telescope. Galaxies, nebulae, super novae -- but there is something peculiar about these images. Where ever we look in space we only see matter. No significant quantities of anti-matter have been found. Since we believe equal amounts of matter and anti-matter have been produced originally we must conclude that there is an asymmetry between particle and anti-particle decays. In the laboratory, however, nature always seems to obey the particle - antiparticle symmetry with one known exception. Almost 40 years ago a small difference has been found in the neutral kaon system. But the nature of this system made it extremely difficult for both theorists and experimentalists to extract a clear picture of this effect. For years there has been great hope in the particle physics community that a large matter - antimatter asymmetry can be observed in a new system - the weak decays of massive B mesons. The past decade has seen a vigorous experimental effort to produce the large quantities of B mesons required to discover the cause of this asymmetry. Particle accelerators have been upgraded and new detectors were constructed. As we enter the Golden Age of B physics nearly a billion B meson decays have been recorded by these experiments. I will review some of the old questions that have been answered and discuss some of the new puzzles that have been uncovered.
ics Colloquium
Friday, April 15, 2005
4:00 PM
Physics Building, Room 204
Marco Mirazita [Host: Simonetta Liuti]
INFN, Laboratori Nazionali di Frascati
"The Search For the Exotic 5 Quark Baryons"
ABSTRACT:
All the well established particles can be classified using the constituent quark model as quark-antiquark states for mesons and 3-quarks states for baryons. However, QCD does not forbid the existence of more complicated internal structures. All the states with quark content different than quark-antiquark or 3-quarks are called "exotic". Exotic particles have been searched for many year in the past, but no positive results have been find until 2003, when several experimental groups reported the first evidences (even if with low statistical significance) for an exotic pentaquark state, the Theta+(1540). On the other hand, several other experiments did not find positive evidence for this state, thus suggesting that, if the Theta+ exists, it should be a really exotic particle. After these first experimental results, several laboratories planned new high-statistic experiments, such those performed and presently under analysis at Jefferson Laboratory. The aim of these experiments is first of all to confirm the existence of Theta+(1540), then to set in an unanmbiguous way its properties. In this talk, a review of the experimental situation will be given, and what we need to conclude that the first exotic baryon has been discovered will be discussed.
ics Colloquium
Friday, April 8, 2005
4:00 PM
Physics Building, Room 204
Al Shapere [Host: Paul Fendley]
University of Kentucky
"Production of Microscopic Black Holes by Cosmic Rays"
ABSTRACT:
Cosmic ray events may create black holes if extra dimensions exist and are sufficiently large. In particular, neutrino cosmic rays may produce black holes deep in the atmosphere, initiating characteristic quasi-horizontal showers far above the standard model rate. The fact that no such showers have been observed to date places an upper bound on the size of these extra dimensions. Continued nonobservation of such events over the next few years would improve these bounds significantly, and sharply limit the rate of black hole production at LHC. On the other hand, if black hole mediated showers are observed in the next few years, they could provide the first experimental evidence for extra dimensions, string theory, and the formation and decay of microscopic black holes.
ics Colloquium
Thursday, April 7, 2005
4:00 PM
Physics Building, Room 204
AVAILABLE
TO BE ANNOUNCED
"TO BE ANNOUNCED"
ics Colloquium
Friday, April 1, 2005
4:00 PM
Physics Building, Room 204
J. E. Thomas [Host: Thomas Gallagher]
Duke University
"High-Temperature Superfluidity in Ultra-Cold Fermi Gases"
ABSTRACT:
An optically-trapped Fermi gas of 6Li atoms becomes strongly interacting when it is tuned to a Feshbach scattering resonance. Such a gas is predicted to be a very high temperature superfluid - the transition temperature is a large fraction of the Fermi energy. I will describe experimental evidence for superfluidity which arises in anisotropic expansion of the gas, in the heat capacity, and in collective damping. These cold Fermi gases provide desktop analogs of exotic, strongly-interacting fermions in nature, from high temperature superconductors and neutron stars to quark-gluon plasmas.
ics Colloquium
Friday, March 25, 2005
4:00 PM
Physics Building, Room 204
E. Paschos [Host: Brad Cox]
University of Dortmund, Germany
"Planetary Models From the Middle Ages"
ABSTRACT:
A small and compact article from AD 1300 describes models for the planets and the moon. It proposes epicyclic theories which deviate from Ptolemy' s Almagest. The Colloquium reviews the models and their accuracy . Then compares them with Arabic models of that time as well as the Newtonian theory. It also demonstrates how scientific knowledge was preserved in the Middle Ages and was transmitted to Italy to spark the beginning of the Copernican Rovolution.
ics Colloquium
Friday, February 18, 2005
4:00 PM
Physics Building, Room 204
Rusi P. Taleyarkhan [Host: Craig Dukes]
The Purdue University
"Acoustic Inertial Confinement Nuclear Fusion - Status and Challenges"
ABSTRACT:
Energetic bubble implosions can generate sonoluminescence (SL) light flashes along with extreme states of compression and temperatures. In cavitation experiments with chilled deuterated acetone, neutron and tritium nuclear emissions were detected, indicative of thermonuclear fusion. The neutron emissions were time correlated with SL light emission. The gamma ray emissions were delayed as would be expected from neutron slowing down and capture. Control experiments with normal acetone did not result in tritium activity or neutron emissions. Fusion was observed during experiments in which the nanoscale nucleation of bubbles was induced in chilled deuterated acetone using a pulse neutron generator as well as with an isotope neutron source. Video images clearly indicate the existing of complex bubble clusters when bubble fusion occurs, and also the formation of comet-like structures which were detrimental to bubble nuclear fusion. Hydrodynamic shock code simulations have supported the experimental findings and indicate temperatures during implosion in the 108K range along with Gbar shock pressures in the imploding bubbles within bubble clusters, but not in single bubble environments. Recent results of experiments will be presented along with discussions related to key technical challenges concerning modeling and experimentation.
ics Colloquium
Friday, February 11, 2005
4:00 PM
Physics Building, Room 204
Rich Superfine [Host: Keith Williams]
University of North Carolina
"NANOMACHINES: From Atomic Lattice Gears to Cystic Fibrosis"
ABSTRACT:
The promise of nanotechnology will be realized through the interplay of new tools and the appreciation of the lessons from biological systems. The challenge of nanomachines ranges from the understanding of the interactions between atomic scale systems to the harnessing of the force generation capabilities of biological systems. We are developing a suite of tools for nanoscale science including the combination of force measurement and manipulation systems in conjunction with scanning probe, electron and optical microscopy. For the basic elements of nanomachines, we have studied gears, springs and electrical contacts of carbon nanotubes. Through the study of carbon nanotube dynamics we have observed that atomic lattices can act like gears in promoting the rolling of nanotubes. Most recently, we have begun a study of nanotubes as torsional springs, have measured the torsional spring constants in freely suspended paddles and have observed strain hardening in individual nanotubes. Finally, biology has developed its own nanomachines and microfluidic systems that include beating cilia to produce flow and complex closed loop feedback mechanisms. We have begun to study this system within a cell culture using a new 3D manipulation system, and will discuss our early results in quantifying the forces applied by beating cilia and studies of the resulting flow.
ics Joint Colloquium; Physics-Astronomy. **PLEASE NOTE ROOM NUMBER CHANGE**
Friday, February 4, 2005
4:00 PM
Physics Building, Room 203
Lawrence Krauss [Host: P.Q. Hung]
Case Western Reserve University
"Life, the Universe, and Nothing: The Future of Life in an Ever-Expanding Universe"
ABSTRACT:
In this talk, I will ruminate on the future of the Universe itself, and also on the future of life within it, using as my starting point recent observations in cosmology. I will first discuss why the Universe we appear to inhabit is the worst of all possible universes, as far as considerations of the quality and quantity of life is concerned. Then, I will describe how fundamental aspects of the way in which we teach cosmology, in particular the relation between geometry and destiny, has been forever altered by recent discoveries. Finally, I will address the fascinating question of whether life might be eternal in an eternally expanding universe. The answer to this question appears to hinge on issues of basic physics, in particular on issues of quantum mechanics and computation, which may determine whether life is ultimately analogue or digital.
ics Colloquium
Friday, January 21, 2005
4:00 PM
Physics Building, Room 204
C. L. (Lew) Cocke [Host: Tom Gallagher]
Kansas State University
"Photon-ion Collisions and Molecular Clocks"
ABSTRACT:
The timing of molecular rearrangemnts can be followed in the time domain on a femtosecond scale by using momentum imaging techniques. Three examples will be discussed: First, the diffraction of electrons ejected from the k-shell of one of atomic constituents of the molecule takes a "picture" of the molecule, and the correlation between the momentum vector of the photoelectron and the subsequent fragmentation pattern is used to estimate the time delay which accompanies the latter process. Second, the kinetic energy release of proton pairs from the double ionizaton of hydrogen by fast laser pulses is timed using the 2.7 fs optical cycle as a clock. The mechanisms of rescattering, sequential and enhanced ionization are clearly identified in the momentum spectra. Pump probe experiments allow us to follow the simultaneous propagation of coherently launched wave packets in different exit channels. Third, the operation of rescattering double ionization in the case of nitrogen and oxygen molecules will be discussed. The use of rescattering to probe the structure of the outer orbitals in molecules will be demonstrated.
ics Colloquium
Friday, December 3, 2004
4:00 PM
Physics Building, Room 204
Alessandro Drago [Host: Simonetta Liuti]
Universita' degli Studi di Ferrara
"Gravitational Waves as a Tool to Investigate Neutron Star Structure"
ABSTRACT:
The new generation of Gravitational Wave detectors, including in particular Laser Interferometers as LIGO, is now becoming fully operative. This will offer the possibility to confirm the existence of the waves predicted by General Relativity and it will also provide the nuclear and astrophysics communities with a new tool to investigate the inner structure of compact stellar objects.
ics Colloquium
Friday, November 19, 2004
4:00 PM
Physics Building, Room 204
Alan Dorsey [Host: Michael Fowler]
University of Florida
"Electronic Liquid Crystals: Novel Phases of Electrons in Two Dimensions"
ABSTRACT:
There is growing experimental evidence that electrons confined to two dimensions (in a semiconductor heterostructure, for instance) at low temperatures and high magnetic fields can display a plethora of partially ordered phases which have the same symmetries as classical liquid crystal phases, such as nematics and smectics. I will review the experimental evidence for these novel quantum phases of matter, discuss several analogous classical systems, and motivate some of the theoretical models for these "quantum Hall liquid crystals".
ics Colloquium
Friday, October 29, 2004
4:00 PM
Physics Building, Room 204
Frank Moss [Host: Acar Isin]
University of Missouri St. Louis
"Random Walks with a Zooplankton"
ABSTRACT:
Theories of swarming and pattern formation have recently become of interest to engineers, chemists and physicists. Interesting examples are offered by various self-propelled biological agents both in simulations and in reality. But well-defined swarming experiments in the lab using real biological agents have been problematic up to now due to size limitations of the animal groups or lack of precise knowledge of the agent-agent or agent-medium interactions. We present the results of lab experiments with the zooplankton /Daphnia/, or “water flea” ­ intermediate in size and complexity between bacteria and birds or fish, for example. Our experiments are compared to predictions of the “Active Brownian Particle” theory developed by a group at Humboldt University in Berlin. /Daphnia/ show the entire range of the theoretically predicted behaviors from single agent to collective motions of swarms and can be observed to perform a fascinating bio-hydrodynamic vortex under certain conditions.
ics Colloquium
Friday, October 22, 2004
4:00 PM
Physics Building, Room 204
Joel Moore [Host: Paul Fendley]
Berkeley
"Hidden Dimensionality in Frustrated Magnets and Complex Superconductors"
ABSTRACT:
The idea that the true dimensionality of a system may differ from its superficial dimensionality appears in many areas of modern theoretical physics. A central theme of recent research in correlated electrons is that two- and three-dimensional materials can, in some cases, show exotic physics familiar from one spatial dimension. Quantum phenomena typically restricted to one dimension, like exact self-duality and a vortex-mediated (Kosterlitz-Thouless) phase transition, can appear in dimensions d>=2 as well. We discuss specific examples of this "dimensional reduction" that are based upon four-spin interactions generated in frustrated magnets and in effective descriptions of some superconductors.
ics Colloquium
Friday, October 15, 2004
4:00 PM
Physics Building, Room 204
Thomas Cohen [Host: Simonetta Liuti]
University of Maryland
"The Science and Sociology of Pentaquarks"
ics Colloquium
Friday, October 8, 2004
4:00 PM
Physics Building, Room 204
Professor Shmuel Nussinov [Host: P.Q. Hung]
Tel Aviv University
"A Physicist Approach to Complex Problems"
ics Colloquium
Friday, October 1, 2004
4:00 PM
Physics Building, Room 204
Jane' Kondev [Host: Paul Fendley]
Brandeis
"The Physics of Confined DNA"
ABSTRACT:
DNA in viruses and in cells is packed in spaces much smaller than its natural size. This state of confinement places interesting constraints on a variety of biological processes DNA is involved in, such as viral infection, gene expression, and recombination. Quantitative experimentation using techniques such as laser tweezers, cryo-electron microscopy and fluorescence spectroscopy has recently begun to probe in detail the confined state of DNA, both in living cells and in the test tube. In this talk I will describe this emerging experimental landscape and outline the theoretical challenges it poses. The particular examples I will focus on will be provided by DNA packing in viruses and gene regulation in bacteria.
ics Colloquium
Friday, September 24, 2004
4:00 PM
Physics Building, Room 204
Milind Diwan [Host: Brad Cox]
Brookhaven National Lab
"New Opportunities in Neutrino Oscillation Physics"
ABSTRACT:
I will describe the remarkable new observations that have transformed our knowledge of the neutrino in the past few years. For over 70 years we knew very little about these particles becuase they are so difficult to detect. Now a new consistent picture has emerged about their basic properties. We can now ask new fundamental questions that might bridge the gap between our knowledge of the quarks and the leptons.
ics Colloquium
Friday, September 10, 2004
4:00 PM
Physics Building, Room 204
Mark Whittle [Host: Peter Arnold]
University of Virginia Astronomy
"Primal Scream- Sounds From the Infant Universe"
ABSTRACT:
Cosmology's extraordinary development shows no signs of slowing down. With the evolution of the Universe's average properties now fairly well understood, the focus has switched to the evoution of perturbations -- how an extremely smooth infant Universe changes into an extremely lumpy old Universe, with galaxies strewn to the horizon. Remarkably, the roots of present day structure can be traced back to sound waves in the early Universe. Even more remarkable, the power spectrum of the sound shows a fundamental and harmonics, as if the Universe were a kind of primitive musical instrument. This talk aims to unpack the relatively new subject of "Big Bang Acoustics", using reproductions of the primordial sound as a vehicle for discussing the physics of that remote time. It turns out that, as with many vibrating objects, the nature of the sound reveals much about the nature of the object as well as the nature of the stimulus.
ics Colloquium
Friday, April 23, 2004
4:00 PM
Physics Building, Room 204
Elliott Lieb [Host: E. Kolomeisky]
Princeton University
"The Dilute, Cold Bose Gas: A truly quantum-mechanical many-body problem"
ABSTRACT:
The peculiar quantum-mechanical properties of the ground states of Bose gases that were predicted in the early days of quantum-mechanics have been verified experimentally relatively recently. The mathematical derivation of these properties from Schroedinger's equation have also been difficult, but progress has been made in the last few years (with R. Seiringer, J-P. Solovej and J. Yngvason) and this will be reviewed. For the low density gas with finite range interactions these properties include the leading order term in the ground state energy, the validity of the Gross-Pitaevskii description in traps, Bose-Einstein condensation and superfluidity in traps, and the transition from 3-dimensional behavior to 1-dimensional behavior as the cross-section of the trap decreases. The latter is a highly quantum-mechanical phenomenon. For the charged Bose gas at high density, the leading term in the energy found by Foldy in 1961 for the one-component gas and Dyson's conjecture of the N^{7/5} law for the two-component gas has also been verified. These results help justify Bogolubov's 1947 theory of pairing in Bose gases.
ics Colloquium
Friday, April 16, 2004
4:00 PM
Physics Building, Room 204
Seunghun Lee [Host: Joe Poon]
National Institute of Standards and Technology
"Unraveling the mysteries in complex oxides by neutron scattering"
ABSTRACT:
Neutron scattering is one of the most powerful tools for studying magnetic and structural properties of solids. It has made seminal contributions in a wide range of fields in condensed matter physics and material science, from high Tc superconductivity, colossal magnetoresistance to quantum magnetism. In this talk, I will begin by introducing the basic principles of elastic and inelastic neutron scattering techniques. I will then describe a few exemplary neutron scattering results from high Tc superconductors and quantum magnets that were crucial to understanding the physics of these systems.
ics Colloquium
Friday, April 2, 2004
4:00 PM
Physics Building, Room 204
Ela Barbaris [Host: Bob Hirosky]
Northeastern University
"TBA"
ics Colloquium
Friday, March 19, 2004
4:00 PM
Physics Building, Room 204
Dr. Kathleen Turner
Dept of Energy, Office of Science, Office of High Energy Physics
"High Energy Physics - On the Ground, Underground, and in Space"
ABSTRACT:
The Office of High Energy Physics' mission is to explore the fundamental nature of matter, energy, space and time. The core of the program centers on investigations of elementary particles and the interactions between them using high energy particle accelerators. In order to fully explore the science, experiments are also done on the ground, underground and in space. The DOE HEP program provides about 90 percent of the federal support for high energy physics research in the U.S. and involves over 2,450 researchers at over 100 universities and 8 laboratories. The High Energy Physics current experimental program will be described, along with a look towards possibilities for the future.
ics Colloquium
Friday, March 5, 2004
4:00 PM
Physics Building, Room 204
John R. Tucker [Host: Olivier Pfister]
Department of Electrical and Computer Engineering - University of Illinois at Urbana-Champaign
"Quantum Computers and Atom-Scale Electronics in Silicon"
ABSTRACT:
Over the past ten years, my colleague T.-C. Shen and I have developed a process for patterning individual phosphorous donors and self-ordered arrays into silicon with atomic resolution. This technique is now employed by the Australian Centre for Quantum Computer Technology and ourselves in efforts to build a silicon quantum computer. Our current research is focused on developing planar single-electron transistors to probe the quantum states of individual P donor 'qubits' inside the silicon crystal. Thus far, we have demonstrated electron wave interference across a 10nm-linewidth Aharanov-Bohm ring. Prospects for realizing a silicon quantum computer will be outlined, along with additional thoughts on future nanoelectronics and transport experiments.
ics Colloquium
Friday, February 20, 2004
4:00 PM
Physics Building, Room 204
Cass Sackett [Host: Thomas Gallagher]
UVA
"Atom Interferometry using Bose-Einstein condensates"
ABSTRACT:
One of the chief applications envisioned for Bose-Einstein condensation is atom interferometry, in which the wave-like nature of a condensate is used to full advantage. A plethora of uses can be imagined, ranging from inertial sensing to probing surfaces. However, a variety of practical and fundamental obstacles must be overcome before condensate interferometry can be competitive with other techniques, even in a research setting. I will discuss our current understanding of these problems and some possible solutions, and report on progress in our experimental effort to build a condensate interferometer.
ics Colloquium
Friday, February 13, 2004
4:00 PM
Physics Building, Room 204
Daniel J. Gauthier [Host: Olivier Pfister]
Duke University - Fitzpatrick Center for Photonics and Communication Systems
"Measuring the Information Velocity in Fast- and Slow-Light Media"
ABSTRACT:
By all accounts, modern science and engineering has a very good understanding of how to use pulses of light to communicate information. It is, after all, the basis for one of the world's biggest and fastest-growing industries. And yet, the fundamental question of how fast information travels remains unanswered. The engineering community, starting with the seminal work by Shannon, has studied information rates, but has essentially ignored the question of the velocity of information. The physics community, initially prompted by an apparent challenge to Einstein's special theory of relativity, has been debating the issue off and on for almost 100 years. Surprisingly, the issue remains unresolved. There is no clear definition of the information velocity because there is only a vague understanding of where information is contained on a waveform. I will review the information velocity debate and present a technique for experimentally measuring the velocity of information for the case were the group velocity of a pulse of light vastly exceeds the speed of light in vacuum (a so-called "fast-light medium") or is much slower than the speed of light in vacuum (a "slow-light medium"). Our research suggests that the information velocity is equal to the speed of light in vacuum, independent of the characteristics of the medium. A tutorial on this topic, including links to recent publications, can be found at: By all accounts, modern science and engineering has a very good understanding of how to use pulses of light to communicate information. It is, after all, the basis for one of the world's biggest and fastest-growing industries. And yet, the fundamental question of how fast information travels remains unanswered. The engineering community, starting with the seminal work by Shannon, has studied information rates, but has essentially ignored the question of the velocity of information. The physics community, initially prompted by an apparent challenge to Einstein's special theory of relativity, has been debating the issue off and on for almost 100 years. Surprisingly, the issue remains unresolved. There is no clear definition of the information velocity because there is only a vague understanding of where information is contained on a waveform. I will review the information velocity debate and present a technique for experimentally measuring the velocity of information for the case were the group velocity of a pulse of light vastly exceeds the speed of light in vacuum (a so-called "fast-light medium") or is much slower than the speed of light in vacuum (a "slow-light medium"). Our research suggests that the information velocity is equal to the speed of light in vacuum, independent of the characteristics of the medium. A tutorial on this topic, including links to recent publications, can be found at: http://www.phy.duke.edu/research/photon/qelectron/proj/infv/
ics Colloquium
Friday, February 6, 2004
4:00 PM
Physics Building, Room 204
Jongsoo Yoon [Host: E. Kolomeisky]
UVA
"Superconductivity in 2-dimension"
ABSTRACT:
Superconductivity occurring in 2-dimension has been understood in the framework of Kosterlitz-Thouless theory, and the nature of the transition is very different from that in 3-dimension. We present our recent data on superconducting properties of ultra-thin tantalum films, and compare with predictions based on the Kosterlitz-Thouless theory. Breakdown of superconductivity near the critical current and new findings on the phenomenon will also be discussed.
ics Colloquium
Friday, January 30, 2004
4:00 PM
Physics Building, Room 204
Nilanga Liyanage [Host: Tom Gallagher]
UVA
"Precision exploration of neutron spin structure at Jefferson Lab Hall A"
ABSTRACT:
Spin structure functions provide basic information about the spin of the quark distributions inside the nucleon. Experimental understanding of the nucleon spin in the kinematic region where the three basic ("valence") quarks dominate the nucleon wave function is still rather poor. Jefferson lab, with its high quality, high polarization continuous electron beam and state of the art polarized nucleon targets in each of its three experimental halls is ideally suited for spin structure measurements in the valence region. An experimental program is underway at Jefferson Lab to measure the spin structure of the nucleon in the valence region with unprecedented precision. The planed upgrade of Jefferson lab CEBAF accelerator to 12 GeV will significantly increase the accessible kinematic range and the precision of these measurements. In this presentation I will give an overview of the neutron spin physics program at Jefferson Lab Hall A. I will also describe new experimental opportunities that will become possible in Hall A with the arrival of 12 GeV beam.
ics Colloquium
Friday, January 23, 2004
4:00 PM
Physics Building, Room 204
Debbie Jin [Host: Thomas Gallagher]
Univ. of Colorado
"Fun with Fermions: Exploring and Manipulating a Fermi Gas of Atoms"
ics Colloquium
Friday, January 16, 2004
4:00 PM
Physics Building, Room 204
John Tranquada [Host: D. Louca]
Brookhaven National Lab.
"Superconductors of a Different Stripe: Charge Inhomogeneity and Superconductivity in Copper Oxides"
ABSTRACT:
The standard model of electronic structure in solids is founded on the notion that electrons inevitably delocalize. In contrast, strong Coulomb repulsion in certain transition-metal oxide compounds can cause electron localization, resulting in the so-called "Mott-insulator" state. Cuprate superconductors consist of electronically-doped Mott insulators. Much of the continuing controversy over how to understand the cuprates concerns the issue of whether one can apply more or less conventional concepts of delocalized electrons, or whether radical new concepts are necessary. I will present experimental evidence, especially from neutron scattering, that the competition been kinetic and Coulomb energies leads to spatial inhomogeneities of charge carriers and antiferromagnetic correlations. It is possible that dynamic inhomogeneities are essential to achieving superconductivity at high temperature.
ics Colloquium
Friday, December 5, 2003
4:00 PM
Physics Building, Room 204
Luis Orozco [Host: Olivier Pfister]
U. of Maryland
"Conditional Dynamics and quantum feedback; an experiment in cavity QED"
ABSTRACT:
Quantum systems that are strongly coupled have fluctuations that are larger than the average value of their steady state. When the fluctuation is a single photon, as is the case in cavity QED, the return to the steady state after the detection of a single photon follows conditional dynamics measurable with quantum optical correlations. The conditional dynamics can be modified, via quantum feedback, based on a single quantum and the knowledge of the conditional state. Work performed in collaboration with J. E. Reiner, W. P. Smith, M. L. Terraciano, and H. M. Wiseman with support from NSF and NIST of the USA.
ics Colloquium
Friday, November 21, 2003
4:00 PM
Physics Building, Room 204
Collin Broholm [Host: Despina Louca]
John Hopkins University
"Quantum Coherence in Magnets"
ABSTRACT:
Magnetic materials are typically found in one of two qualitatively different states: Thermally disordered at high temperatures or spin ordered at low temperatures. In this talk I describe a third distinct state of an interacting spin system: quantum ordered magnetism. I present neutron scattering data that provide evidence for quantum order in zero, one, two, and three-dimensional spin systems. La4Cu3MoO12 contains spin-trimers that develop quantum order at low temperature where each trimer becomes a composite spin-1/2 degree of freedom. Y2BaNiO5 is an antiferromagnetic spin-1 chain with an extensive one-dimensional Haldane ground state. I present scattering data that provide clear evidence for long range coherence in the absence of conventional spin order2. (C4H12N2)Cu2C16 (PHCC) is a frustrated bi-layer antiferromagnet with interactions that span a two-dimensional plane. I show that there are coherent triplet excitations and argue that competing interactions favor quantum order over spin order3. Cu2(C5H12N2)2Cl4 (CuHpCl) has a cooperative singlet ground state and was initially thought to be a spin ladder. However, neutron scattering data show that it is in fact a three dimensional frustrated system with quantum order. Apart from describing and comparing the low temperature quantum ordered states in these pure systems, I shall also touch on the fascinating effects of impurities5 and the field driven quantum phase transitions that can be accessed experimentally in several of these systems.

REFERENCES
1. Y. Qiu, C. Broholm, S. Ishiwata, M. Azuma, M. Takano, R. Bewley, and W. J. L. Buyers, cond-mat/0205018.
2. Guangyong Xu, J. F. DiTusa, T. Ito, H. Takagi, K. Oka, C. Broholm and G. Aeppli, Phys. Rev. B 54, R6827 (1996).
3. M. B. Stone, I. A. Zaliznyak, Daniel H. Reich, and C. Broholm, Phys. Rev. B 64, 144405 (2001).
4. M. B. Stone, J. Rittner, Y. Chen, H. Yardimci, D. H. Reich, C. Broholm, D. V. Ferraris, and T. Lectka, Phys. Rev. B 65, 064423 (2002).
5. M. Kenzelmann, G. Xu, I. A. Zaliznyak, C. Broholm, J. F. DiTusa, G. Aeppli, T. Ito, K. Oka, and H. Takagi. Phys. Rev. Lett. 90, 087202 (2003).
6. Y. Chen, Z. Honda, A. Zheludev, C. Broholm, K. Katsumata, and S. M. Shapiro Phys. Rev. Lett. 86, 1618 (2001).

ics Colloquium
Friday, November 14, 2003
4:00 PM
Physics Building, Room 204
Peter Arnold [Host: E. Kolomeisky]
UVA
"The BEC transition temperature of dilute gases: a not-so-simple problem in statistical mechanics"
ABSTRACT:
The phase transition temperature for Bose-Einstein condensation of a three-dimensional ideal gas of bosons at fixed density is something that every physicist learns to calculate in graduate school, if not before. Amusingly, the first correction to that result, from arbitrarily weak interactions, is sufficiently challenging that only now is there beginning to appear some theoretical agreement on its magnitude, roughly 80 years after Einstein computed the ideal gas result.
ics Colloquium
Friday, November 7, 2003
4:00 PM
Physics Building, Room 204
Paul Kwiat [Host: Olivier Pfister]
U of Illinois, Urbana-Champaign
"Entangled Photons for Quantum Information: 101 uses for a Schroedinger cat"
ABSTRACT:
We have developed a means of producing entangled pairs of photons, using the process of spontaneous parametric downconversion in a novel two-crystal geometry. The quality of the source has enabled us to produce states of unparalleled purity, while the brightness has permitted an extreme violation of Bell's inequalities. Furthermore, the source is tunable, and we have been able to produce for the first time non-maximally entangled states, and states of arbitrary purity. The result is the capability to produce (almost) any two-photon quantum (polarization) state. Such states have application to such problems in quantum information as quantum cryptography, quantum teleportation, and quantum cooking.
ics Physics and Materials Science Joint Colloquium
Friday, October 24, 2003
4:00 PM
Physics Building, Room 204
Dr. Stuart A. Wolf [Host: Joe Poon and James Groves]
University of Virginia, and DARPA at Arlington, VA
"A new spin on electronics - spintronics"
ABSTRACT:
Until very recently, the spin of the electron was ignored in mainstream electronics. The discovery of the giant magnetoresistance (GMR) effect in magnetic multilayers in 1988 and the subsequent development of sensors based on it began a transformation that will soon provide new paradigms for electronics for the new millenium. This talk will concentrate on the evolution of the DARPA spin electronics or spintronics project. The motivation, the science and the remarkable prospects for the future will be described in some detail.
ics Colloquium
Friday, October 17, 2003
4:00 PM
Physics Building, Room 204
Qaisar Shafi [Host: P. Q. Hung]
Bartol Institute
"Where does the Standard Model come from"
ABSTRACT:
The Standard Model (SM) provides a highly successful description of strong, weak and electromagnetic interactions at present energies. In combination with Einstein's general relativity, it helps lay the foundation of another successful theory, the hot big bang cosmology. Some recent attempts to go beyond this theoretical framework will be discussed, necessitated in part by some exciting experimental discoveries, namely neutrino oscillations, existence of non-baryonic dark matter, CMB anisotropy,etc.
ics Colloquium
Friday, October 10, 2003
4:00 PM
Physics Building, Room 204
Herb Fertig [Host: E. Kolomeisky]
University of Kentucky
"The Quantum Hall Bilayer: A New Superfluid"
ABSTRACT:
Superfluids and superconductors are known to possess a unique stiffness related to the phase of their groundstate wavefunctions. Under appropriate circumstances, double layer quantum Hall systems possess an analogous stiffness that may be understood in terms of a condensation of particle-hole pairs. The relation between these systems has motivated both theoretical and experimental efforts to find properties in the bilayer quantum Hall system usually associated with superfluids. Most prominently, an effect reminiscent of Josephson tunneling has been observed in experiments with high quality samples, although there is considerable dissipation whose origin is not understood. Using a renormalization group analysis and results from Langevin dynamics simulations, we demonstrate that the likely source of dissipation is vortices in the phase degree of freedom. Vortex pairs are shown to have a very unusual thermal deconfinement transition in this system, and can also be broken apart at low temperature by disorder. In the latter case, simulations show the system possesses properties reminiscent of a glassy state which qualitatively account for many of the experimental observations.
ics Colloquium
Friday, September 12, 2003
4:00 PM
Physics Building, Room 204
Professor Chris Quigg [Host: Brad Cox]
Fermi National Accelerator Laboratory
"Envisioning Particles and Interactions"
ABSTRACT:
I will present a new way to envision the particles and interactions: a pair of interpenetrating tetrahedra that we might call the double simplex, in homage to the double helix that has just celebrated its fiftieth anniversary. Any chart or mnemonic device should be an invitation to narrative and a spur to curiosity, and that is what I intend for the double simplex. My goal is to represent what we know is true, what we hope might be true, and what we don't know--in other terms, to show the connections that are firmly established, those we believe must be there, and the open issues. I want also to express the spirit of play, of successive approximations, that animates the way scientists work.
ics Colloquium
Friday, April 25, 2003
4:00 PM
Physics Building, Room 204
Prof. John Malko [Host: Oscar Rondon]
Emory University
"How a doctor of particle physics found happiness working with 'real doctors'"
ics SPECIAL PHYSICS AND ASTRONOMY COLLOQUIUM
Friday, April 18, 2003
4:00 PM
Physics Building, Room 204
Tom Abel [Host: P. Q. Hung]
Pennsylvania State Univ.
"The First Stars in the Universe"
ABSTRACT:
Recent progress in our ability to follow numerically the formation of the first objects in the universe predict the first stars to massive and to form in isolation. They are copious producers of UV radiation and begin to reionize the intergalactic medium. The single currently allowed model for structure formation turns out to be able to match all aspects of the most recent accurate measurements of the cosmic microwave background radiation. In this talk we highlight our new understanding of the physics of the formation of the first stars, their lifes, their remnants and their impact on subsequent structure formation.
ics Colloquium
Friday, April 11, 2003
4:00 PM
Physics Building, Room 204
Sean Washburn [Host: Joseph Poon]
University of North Carolina at Chapel Hill
"Nanotechnology, nanotubes and molecules as tinker toys"
ABSTRACT:
Nanotechnology holds many promises for the future and many (possibly insurmountable) challenges before the promises can be implemented. Carbon nanotubes with their superb mechanical and electrical properties are a canonical example of both of these aspects. The possibility of assembling them into designed forms as new materials or or into nanometer mechanical and electrical devices might lead to improved strengths, speeds, etc. Some elementary experiments indicate that while the promise is still great, the barriers to implementing such nano-devices are still ahead of us. The methods of the experiments already have shown that many academic disciplines and new techniques will be involved in invoking the new improvements. Some examples of such efforts will be reviewed.
ics Colloquium
Friday, April 4, 2003
4:00 PM
Physics Building, Room 204
Leslie Camilleri [Host: Craig Dukes]
Fermilab/CERN
"The Fascination of Neutrino Oscillations: Their discovery and their future study"
ABSTRACT:
Anomalies have been observed in both solar and atmospheric neutrinos. How the study of these anomalies has led to the discovery of neutrino oscillations will be summarized. Many experiments are now being built to further our understanding of these oscillations. These experiments, and the next generation of experiments being planned to complete our understanding of how neutrinos mix and what their mass spectrum is, will be described.
ics Colloquium
Friday, March 21, 2003
4:00 PM
Physics Building, Room 204
Ganpathy Murthy [Host: Eugene Kolomeisky]
University of Kentucky
"Interactions and Disorder in Quantum Dots: A New Large-g Approach"
ABSTRACT:
Understanding the combined effects of disorder and interactions in electronic systems has emerged as one of the most challenging theoretical problems in condensed matter physics. It turns out that one can solve this problem non-perturbatively in both disorder and interactions in the regime when the system is finite (as in a quantum dot) but its dimensionless conductance g under open-lead conditions is large. This regime is experimentally interesting for the statistics of Coulomb Blockade in quantum dots and persistent currents in rings threaded by a flux. First some RG work will be described which shows that a disordered quantum dot with Fermi liquid interactions can be in one of two phases; one controlled by the so-called Universal Hamiltonian and another regime where interactions become large. These two are separated in the infinite-g limit by a second-order phase transition. I will show how to solve for the strong-coupling phase, which is characterized by a Fermi surface distortion, by a large-N approximation (where N=g is in fact large for realistic systems). Predictions will be presented for finite but large g for the statistics of the Coulomb Blockade peak spacings and other correlators. Finally, the relationship of these results to puzzles in persistent currents in mesoscopic rings will be presented.
ics Colloquium
Friday, March 14, 2003
4:00 PM
Physics Building, Room 204
Dinko Pocanic [Host: Eugene Kolomiesky]
University of Virginia
"A new look at rare pion and muon decays"
ABSTRACT:
Pion and muon, the lightest unstable particles, were discovered more than fifty years ago, and have been well studied since. However, over time the Standard Model (SM) of elementary particles and interactions has become so successful that for several key pion and muon properties its predictions are far less uncertain than the best available measurements, primarily those concerning the particles' rare decay modes. Thus, slight deviations from the SM predictions can provide valuable clues to new physics outside of the current SM.

In its first phase, the PIBETA experiment has measured accurately several such rare decays at PSI, the Swiss meson facility. The talk will focus on the motivation, experimental apparatus, method, and the unexpected first results of these measurements.
ics Colloquium
Friday, February 21, 2003
4:00 PM
Physics Building, Room 204
Philip Phillips [Host: Jongsoo Yoon]
UIUC
"The Illusive Bose Metal"
ABSTRACT:
Cooper pairs (bosons) are thought to exist in two quite distinct ground states: 1) localized in a Mott insulator or 2) condensed in a superconductor. However,recent experiments on 2D insulator-superconductor transitions indicate that there may be a third possibility: a metal with a finite resistivity at zero temperature. I will review the standard theoretical framework used to understand the insulator-superconductor transition, the recent experimental results and I will show quite generally how bosons lacking phase coherence can form a metal in the presence of disorder rather than an insulating phase. The metallic state is rather weird, however. The phase degrees of freedom are glassy. At the heart of the metallic state is the dissipation inherent in the glassy state. Bosons moving in such a glassy environment fail to localise because no true ground state exists.
ics Colloquium
Friday, February 14, 2003
4:00 PM
Physics Building, Room 204
Robert Bryant [Host: Bascom Deaver]
UVA - Chemistry
"Nuclear Spin Relaxation, Dispersion, and Intermolecular Exploration"
ics Colloquium
Friday, February 7, 2003
4:00 PM
Physics Building, Room 204
Rolf Sharenberg [Host: Ken Nelson]
Purdue University - (E-735 Collaboration)
"Experimental evidence for hadronic deconfinement in pbar-p collisions at 1.8 TeV"
ABSTRACT:
We have measured deconfined hadronic volumes, 4.4 < V < 13.0 fm3, produced by a one dimensional (1D) expansion. These volumes are directly proportional to the charged particle pseudorapidity densities 6.75 < dNc/d0 < 20.2. The hadronization temperature is T = 179.5±5(syst) MeV. Using Bjorken's 1D model, the hadronization energy density is F = 1.10±0.26(stat) GeV/fm3 corresponding to an excitation of 24.8±6.2(stat) quark–gluon degrees of freedom.
ics Colloquium
Friday, January 31, 2003
4:00 PM
Physics Building, Room 204
Amy Bug [Host: Simonetta Liuti]
Swarthmore College
"Gender and Physics: a Hard Look at a Hard Science"
ics Colloquium
Friday, January 24, 2003
4:00 PM
Physics Building, Room 204
David Divincenzo [Host: Olivier Pfister]
IBM
"Prospects for Quantum Computation"
ABSTRACT:
A "standard model" for the physical implementation of a quantum computer was laid out some years ago. It indicated a set of capabilities that had to be achieved to make quantum processing possible: 1) systems with well-characterized qubits must be constructed. 2) These qubits should be initializable to the "0" state. 3) It must be possible to control the one- and two-qubit Hamiltonian of the system, so that unitary quantum logic gates are enacted. 4) Decoherence and imprecision of gate operations must be kept very low. 5) Reliable measurements of the quantum state of individual qubits must be possible. In this talk I will indicate progress towards these goals, after first reviewing why we want to do quantum computation.
ics Colloquium
Friday, November 22, 2002
4:00 PM
Physics Building, Room 204
David DeMille [Host: Cass Sackett]
Yale
"Tabletop probes for TeV physics: searches for the electric dipole moment of the electron"
ABSTRACT:
Remarkably, the virtual exchange of exotic heavy particles--such as those predicted to exist in supersymmetric and grand unified theories-- can lead to observable effects in ordinary matter. This talk will describe a set of experiments searching for such an effect: namely, a permanent electric dipole moment along the spin of the electron. The most sensitive experiments of this type are already sensitive to new physics at the TeV scale, and set important limits on possible extensions to the standard model. I will report on our progress in developing a new technique, which promises several orders of magnitude improvement in sensitivity.
ics Colloquium
Friday, November 15, 2002
4:00 PM
Physics Building, Room 204
Konstantin Matveev [Host: Eugene Kolomeisky]
Duke University
" 0.7-anomaly in Quantum Point Contacts A"
ABSTRACT:
A remarkable property of one-dimensional conductors is the quantization of their resistance in units of Planck constant divided by the square of the elementary charge. This effect is well understood and readily observed in low-temperature experiments with relatively short one-dimensional conductors called the quantum point contacts. A puzzling feature of the transport through such contacts was reported a few years ago, when it was discovered that at somewhat higher temperatures the conduction drops to about 0.7 of its quantized value. This phenomenon, often referred to as the 0.7-anomaly, has been studied extensively in the last few years. I will discuss the latest experimental data and the theoretical attempts at understanding this effect.
ics Colloquium
Friday, November 8, 2002
4:00 PM
Physics Building, Room 204
Jerry Blazey [Host: Bob Hirosky]
NIU
"Physics at DZERO: Exploring the Microscopic Structure of the Universe"
ABSTRACT:
To explore the microscopic structure of the universe very energetic beams of submicroscopic particles and complicated detectors, such as the DZERO detector, are required. These huge machines, built by graduates students, physicists, and engineers, have the potential to explain the origins of mass and to explore extra spatial dimensions. The technology behind these investigations and their current state will be described. Prof. Blazey serves as spokesman for the D-Zero Collaboration at Fermilab and director of NICADD, the Northern Illinois Center for Accelerator and Detector Development.
ics Colloquium
Friday, October 25, 2002
4:00 PM
Physics Building, Room 204
Randy Hulet [Host: Cass Sackett]
Rice University
"Tunable Interactions in Ultracold Bose and Fermi Gases - Solitons to Superfluids"
ABSTRACT:
Bose-Einstein condensation of ultracold atomic gases, first achieved only seven years ago, has lead to remarkable demonstrations of matter wave phenomena. One of the most compelling aspects of ultracold atoms is the experimental ability to alter the strength and even the sign of the interactions between atoms using magnetically tuned "Feshbach resonances". We have exploited this tunability to create matter wave solitons composed of Bose-Einstein condensates of lithium atoms [1]. A similar experiment was performed in Paris [2]. Soliton waves arise when a nonlinearity exactly compensates for wavepacket dispersion. This compensation enables a soliton to propagate without spreading. Solitons are observed in a variety of physical systems, including water waves, plasma waves, and optical pulses, to name but a few. The nonlinearity in ultracold atoms arises from their interactions. By changing the interactions from repulsive to attractive, the condensate is observed to form a multi-soliton "train" of up to 15 individual solitons. The solitons maintain their size and shape for a propagation time of up to 3 s. Adjacent solitons are observed to interact repulsively. We are also pursuing the possibility of creating Cooper pairs of fermionic 6Li atoms, which would be an atom analog of superconductivity, in the gas phase. The necessary attraction would again be generated using a Feshbach resonance, which could enable the first exploration of superconductivity in the strong coupling regime. [1] K.E. Strecker, G.B. Partridge, A.G. Truscott, R.G. Hulet Nature 417, 150 (2002). [2] L. Khaykovich et al., Science 296, 1290 (2002).
ics Colloquium
Friday, October 18, 2002
4:00 PM
Physics Building, Room 204
Siyuan Han [Host: B. Shivaram]
Department of Physics and Astronomy, University of Kansas
"Superconducting Schrodingers Cat and its Application to Quantum Computing"
ABSTRACT:
Since the beginning days of quantum mechanics the possibility of having coherent superposition of macroscopic quantum states, e.g., Schrodingers Cat, has stimulated much theoretical debates. The idea can actually be tested out experimentally in superconducting electronic devices called Josephson junctions (JJs) and SQUIDs. Ill show that when sufficiently isolated from environments a current biased JJ is a very well characterized and controllable macroscopic quantum system and that Rabi oscillations can be utilized to create coherent superposition of macroscopic quantum states. In a recent experiment, we have succeeded in placing a JJ in the superposition of its ground (alive) and excited (dead) states and observing its time evolution as it oscillates coherently between the alive and dead states of the junction [Y. Yu et al., Science 296, p889 (May 2002)]. The coherence time, estimated from the exponentially decaying amplitude of the oscillations, is about 5 s which is very promising for quantum computing using the phase qubits (JJs) or flux qubits (SQUIDs).
ics Colloquium
Friday, October 4, 2002
4:00 PM
Physics Building, Room 204
Professor Paul Avery [Host: Brad Cox]
University of Florida
"Global Data Grids for Data Intensive Science"
ics Colloquium
Friday, September 20, 2002
4:00 PM
Physics Building, Room 204
Greg Landsberg [Host: P. Q. Hung]
Brown University
"Black Holes at Future Colliders and Beyond"
ABSTRACT:
If the scale of quantum gravity is as low as a TeV, as was proposed by Arkani-Hamed, Dimopoulos, and Dvali a few years ago, one of the most dramatic manifestation of this fact would be copious production of miniature black holes at the CERN's LHC accelerator, qualifying the latter as black-hole factories. These rapidly evaporating black holes could serve as sensitive probes of quantum gravity effects, topology of extra dimensions, and as a laboratory to produce new particles with the mass ~100 GeV. I'll discuss the black hole production and decay mechanisms at future colliders and the opportunities of cosmic ray detectors in observing black holes in ultra-high-energy cosmic ray collisions. Using the Higgs boson as an example, I'll demonstrate that it can be found in the decays of black holes as early as in the first hour of operation of the LHC, even with incomplete detectors.
ics Colloquium
Friday, September 13, 2002
4:00 PM
Physics Building, Room 204
Prof. Puru Jena [Host: Joseph Poon/Louis Bloomfield]
Virginia Commonwealth University
"The Role of Clusters in the Design of Nano-Scale Systems"
ABSTRACT:
Atomic clusters consisting of a few to a few thousand atoms constitute a new phase of matter intermediate between atoms and solids. Unlike conventional nanostructured materials, the size and composition of these clusters can be controlled one atom at a time. The properties of such clusters brought about by their large surface-to-volume ratio, unique geometry, low dimensionality and reduced coordination, exhibit novel behavior quite unlike that in the bulk. For example, metallic elements can be made to form ionic bonds while nonmagnetic and anti-ferromagnetic materials can become ferromagnetic or ferrimagnetic. This talk will introduce the principles for designing these clusters and discuss a concept where clusters can be viewed as super-atoms - adding a third dimension to the periodic table. Recent experimental evidence to support this idea will be presented. Examples of cluster assembled materials will include high-energetic materials involving Al(MnO4)3, alkali metal clusters isolated in zeolites, transition metal clusters supported on organic and metallic substrates, and manganese-oxide clusters passivated by acetate ligands. Ultimately the properties of crystals composed of clusters as the building blocks will be discussed. It is hoped that the synergy between theory and experiment will lead to the synthesis of cluster assembled materials with unique and tailored properties, thus creating new opportunities in materials science at the dawn of the new millennium.
ics Colloquium
Friday, April 26, 2002
4:00 PM
Physics Building, Room 204
Sidney A. Coon [Host: S. Liuti]
NSF and New Mexico State University
"A Singular Potential:from Theorist's Toy to Experimental Realization"
ABSTRACT:
The inverse square potential (V(r)~1/r**2), first studied by Cote, a contemporary of Isaac Newton, is an interesting potential for nonrelativistic quantum mechanics. It lies on the edge of the line dividing potentials which can be treated in the familiar manner and those which are singular. Singular potentials have been studied for a long time because they can be regarded as models for nonrenormalizable field theories, and, more recently, as an element of the new paradigm of effective field theory methods in nuclear physics. In this talk, I will demonstrate the mathematics of the 1/r**2 potential, including the anomalous (quantum mechanical) breaking of scale symmetry and a rigorous treatment of absorption ("fall to the center"). Correct mathematics leads to a quantum mechanical understanding of the formation of anions (electrons bound by the dipole moment of a polar molecule) and of a very recent dedicated experimental study of this potential in the context of manipulation of cold atoms.
ics Colloquium
Friday, April 19, 2002
4:00 PM
Physics Building, Room 204
Larry Cardman [Host: T. Gallagher]
JLab
"Building Nucleons and Nuclei from Quarks and Glue: Early Results from the Research Program at Jefferson Lab"
ics Colloquium
Friday, April 12, 2002
4:00 PM
Physics Building, Room 204
Thomas Gallagher [Host: Eugene Kolomeisky]
University of Virginia
"Spontaneous evolution from a cold Rydberg gas to an ultra cold plasma"
ics Colloquium
Friday, March 29, 2002
4:00 PM
Physics Building, Room 204
A. Marchionni [Host: S. Conetti]
Fermi Lab
"Long baseline neutrino oscillation experiments: why and how"
ABSTRACT:
The evidence for neutrino oscillations from the SuperKamiokande experiment still leaves several open questions. The present program of long baseline neutrino oscillation experiments will address these issues. The ongoing K2K experiment and the future JHF facility in Japan, the programs in preparation in the United States (MINOS) and in Europe (CNGS) will be reviewed. MINOS (Main Injector Neutrino Oscillation Search) will be operating at the beginning of 2005 over a baseline of 735 km from FERMILAB (Illinois) to Soudan (Minnesota). Status and goals of the MINOS experiment will be reported in detail.
ics Colloquium
Friday, March 22, 2002
4:00 PM
Physics Building, Room 204
Dr. Bruce Van Dover [Host: Joseph Poon]
Agere Systems , Murray Hill NJ
"High-performance dielectric thin films for science and technology"
ABSTRACT:
Ultrahigh-density dynamic random acess memory, hyperscaled field-effect transistors, and field-effect-induced superconductivity at 117 K in fullerenes are examples where high-performance thin film dielectrics play a pivotal role in science and technology. In the past, only a small set of materials (SiO2, Al2O3, (Ba,Sr)TiO3, etc.) have been considered for these structures. We have assessed a wide range of dielectric systems using a high-throughput, composition-spread approach. This has lead to the discovery and development of dielectrics with extremely high performance, as well as the identification of unexpected physics by careful investigation of systematic trends. I will discuss the scientific and technological issues, our approach to discovery, and the interesting materials and materials physics we have uncovered.
ics Colloquium
Friday, March 8, 2002
4:00 PM
Physics Building, Room 204
Julian Noble [Host: E. Kolomeisky]
University of Virginia
"Running Out of Time: Why Elephants Don't Gallop"
ABSTRACT:
Newtonian physics implies that running is impossible for sufficiently large animals. There are two main factors that influence this:

1. An animal's strength/weight ratio decreases with size, hence a sufficiently large animal will be liable to injury if it attempts a gallop.

2. The time required for an animal to move its limbs increases with size, but the time an animal can remain in the air (while running) does not scale with linear dimension. Therefore there is some size beyond which an animal has "run out of time" and cannot take advantage of a running gait. These aspects of the biomechanics of locomotion bear on the interesting questions of determining the speeds of extinct species, as well as how varying gravity affects locomotion.
ics Colloquium
Friday, March 1, 2002
4:00 PM
Physics Building, Room 204
N.O. Lipari [Host: V. Celli]
Lipari Int'l Consulting
"Physicists and Industry in the 21st Century: Who, What, How"
ABSTRACT:
The on-going global economic transformations require that industries strongly focus on innovation, time to market, quality and cost in the introduction of new products. The trend in each industry is to focus on core competencies and obtain the additional resources from external alliances and partnerships with Universities and Government. "Coopetition" is emerging as the most effective approach for technology transfer, i.e. the path from idea to products. This requires a totally different and much more pervasive role of the physicist. In addition to the scientific skills, the scientist needs interdisciplinary and communication skills in order to successfully interact in the industrial environment. Examples will be given. Specific suggestions for the role of the university in forming the physicists with the proper requirements for the modern industry will be discussed.
ics Colloquium
Friday, February 22, 2002
4:00 PM
Physics Building, Room 204
Kareljan Schoutens [Host: Paul Fendley]
University of Amsterdam
"New States of Matter in the Quantum Hall and BEC Regimes "
ics Colloquium
Friday, February 15, 2002
4:00 PM
Physics Building, Room 204
Despina Louca [Host: T. Gallagher]
University of Virginia
"Lattice Effects and Jahn-Teller Fluctuations in Crystals"
ABSTRACT:
In many systems i.e. magnetoresistive and superconducting oxides, the atomic structure couples strongly to the electronic degrees of freedom. In CMR crystals, Jahn-Teller effects are strongly related to the metal-insulator transition, for instance. The manganites are one example where the JT distortions are static and are important ingredients to the polaron lattice formation. In cuprates, when static distortions are present it usually means superconductivity is killed, while dynamic effects prevailing in the SC phase are sometimes too fast to observe. (La/Sr)CoO3 serves as a prototype for studying the crossover from static to dynamic effects. With the pair density function analysis and inelastic S(Q,w) measurements, it was determined that dynamical JT fluctuations induce a distorted atomic structure. The S(Q,w) clearly shows the presence of localized phonon modes most likely due to JT excitations, while the local structure transforms to an unusually glassy state that is intermediate to the manganites and cuprates.
ics Colloquium
Friday, February 8, 2002
4:00 PM
Physics Building, Room 204
Jun Ye [Host: T. Gallagher]
JILA
"Light: Time Meets Frequency"
ics Colloquium
Friday, February 1, 2002
4:00 PM
Physics Building, Room 204
Michael Turner [Host: Craig Dukes]
University of Chicago
"Making Sense of the New Cosmology"
ABSTRACT:
Cosmology is in its most exciting period of discovery yet. Over the past five years we have determined the basic features of the Universe -- spatially flat; accelerating; composed of 1/3rd a new form of matter, 2/3rds a new form of energy, with some ordinary matter and neutrinos; and apparently born from a burst of rapid expansion during which quantum noise was stretched to astrophysical size seeding cosmic structure. Now we have to make sense of this: What is the dark matter particle? What is the nature of the dark energy? Why this mixture? How did the matter -- antimatter asymmetry arise? What is the underlying cause of inflation (if it occurred)? If we succeed in making sense of our Universe, this will truly be remembered as a Golden Age.
ics Colloquium
Friday, January 25, 2002
4:00 PM
Physics Building, Room 204
Olivier Pfister [Host: T. Gallagher]
University of Virginia
"Quantum information with quantum fields: creation and entanglement of twin beams of light"
ABSTRACT:
The concept of quantum information can be seen as stemming from the fascinating idea of putting quantum mechanics to practical use as such, and not only as the theory behind, in particular, microscopic physics. Because of the latter, it is sometimes believed that experimental efforts in quantum information only involve exquisite control over nanoscale entities such as single atoms or single photons (see last week's colloquium for a beautiful illustration). This is not rigorously true, as qubits can also be implemented using exquisitely controlled macroscopic entities, such as optical fields of milliwatt power. In this talk, I will present our endeavor to create bright entangled light sources suitable for quantum teleportation and quantum error correction, as well as our contribution to the theoretical understanding of such problems.
ics Colloquium
Friday, January 18, 2002
4:00 PM
Physics Building, Room 204
Daniel Gammon [Host: O. Pfister]
Naval Research Lab.
"Optically probing and controlling a single quantum dot"
ics Colloquium
Friday, December 7, 2001
4:00 PM
Physics Building, Room 204
Swapan Chattopadhyay [Host: Donal Day]
JLAB
"New Dimensions in Probing the Structure and Function of Matter: Concepts, Techniques and Technologies"
ABSTRACT:
We will explore various concepts, techniques and technologies for producing ultrashort pulses of electrons and photons of all energies and colors from the femtosecond to the attosecond duration and beyond for breakthrough research in physics, chemistry, life and information sciences
ics Colloquium
Friday, November 30, 2001
4:00 PM
Physics Building, Room 204
Andrew Hime [Host: Craig Dukes]
Los Alamos
"Results from the Sudbury Neutrino Observatory"
ABSTRACT:
The Sudbury Neutrino Observatory (SNO) is a heavy water, imaging Cerenkov detector operating 6800 feet underground in the Creighton Nickel Mine in Ontario, Canada. With its heavy water target, SNO has the unique capability to detect and separate three distinct 8B solar neutrino signals through the charged current (CC), neutral current (NC), and elastic scattering (ES) channels. By comparing the solar neutrino flux deduced from the CC interaction (sensitive only to electron neutrinos) with that deduced from the NC or ES interactions (sensitive to all active neutrino flavors), SNO can make a unique study of the solar neutrino deficit and a model independent test for neutrino oscillations. Results from the pure D2O phase of SNO will be presented along with their implications for elementary particle physics, astrophysics, and cosmology.
ics Colloquium
Friday, November 16, 2001
4:00 PM
Physics Building, Room 204
Michael Duff [Host: P. Q. Hung]
University of Michigan
"A Layman's Guide To M-Theory"
ABSTRACT:
Superunification of the fundamental interactions underwent a major paradigm shift in 1984 when eleven-dimensional supergravity was knocked off its pedestal by ten-dimensional superstrings. 1995 witnessed another shift of equal proportions, however, when superstrings were themselves superseded by ``M-theory'', a non-perturbative theory which describes extended objects with two dimensions (supermembranes) and five dimensions (superfivebranes), which subsumes all five consistent string theories and whose low-energy limit is, ironically, eleven-dimensional supergravity.
ics Colloquium
Friday, November 9, 2001
4:00 PM
Physics Building, Room 204
Mariano Quiros [Host: P. Q. Hung]
Istituto de Estructura de la Materia (CSIC), Madrid, Spain
"The Long Way From Strings To Large Extra Dimensions "
ABSTRACT:
In the first part of the talk I will review the main ideas going from string models to the possibility of low string scales and large extra dimensions. In particular the subjects of bosonic and fermionic strings (IIA, IIB, heterotic and type I/I'), T-duality and D-branes, will be covered. In the second half of the talk I will describe the different scales which can appear in the various string constructions and provide the experimental constraints on transverse (gravitational) and longitudinal (gauge) dimensions using gravitational and collider data.
ics Colloquium
Friday, November 2, 2001
4:00 PM
Physics Building, Room 204
Chris Monroe [Host: Robert Jones]
University of Michigan
"Building a quantum computer atom by atom"
ABSTRACT:
A quantum computer can store and process quantum superpositions of numbers. This parallelism leads to an exponential speedup over conventional computers for certain algorithms. However, the prospects for constructing a quantum computer are highly speculative, owing to the extremely fragile nature of quantum superpositions. A quantum computer is nothing more than a smaller (and more humane) version of Schroedinger's Cat, and if one is ever built, it will strongly impact both computer science and fundamental quantum mechanics. A leading physical candidate for a quantum computer is a collection of individual trapped atoms, controlled and manipulated with optical fields. Experiments are reported in this context, including the demonstration of simple quantum logic gates and the controlled generation of entangled quantum states. The outlook for future quantum computing with atoms or alternative technologies will be discussed.
ics The Llewellyn G. Hoxton Lecture Please not time and place


Monday, October 29, 2001
7:30 PM
Chemistry Building , Room 402
Gerald 't Hooft [Host: Department of Physics]
University of Utrecht
"The Universe of the Elementary Particles"
ics Colloquium
Friday, October 26, 2001
4:00 PM
Physics Building, Room 204
G. 't Hooft [Host: P. K. Kabir]
University of Utrecht, Netherlands
"How does God Play Dice?
(Speculations about Quantum Mechanics at the Planck scale)"
ABSTRACT:
Attempts to arrive at consistent theories combining Quantum Mechanics with General Relativity not only require new concepts of space, time and matter, such as the ideas that lead to Superstring Theory, D-brane theory and M-theory, but they may also require a reconsideration of what Quantum Mechanics itself really is about. Although completely deterministic scenarios appear to be ruled out by the Bell inequalities, it is nevertheless worth-while to investigate a set-up where we start with a deterministic theory and add to this the notion of information loss. Although models proposed so-far all show deficiencies of some sort which makes them unrealistic for describing the real world, these models do show how chaotic phenomena in a deterministic theory might be suspected to lie at the basis of the quantum nature of our world.
ics Colloquium
Friday, October 19, 2001
4:00 PM
Physics Building, Room 204
Michael Widom [Host: Joe Poon]
Carnegie Mellon University
"Entropy in the Solid State"
ABSTRACT:
Equilibrium states of matter balance the thermodynamic tendency to minimize energy with the simultaneous need to maximize their entropy. Depending on the temperature, different equilibrium states may occur representing different tradeoffs between energy and entropy, leading potentially to a multiplicity of solid state phases. The phase diagram of a superalloy and of the element Pu illustrate the importance of entropy residing in modes of atomic vibrations. Additional examples will be given of quasicrystal- and glass-forming alloys in which the entropy resides instead in novel discrete configurational degrees of freedom.
ics Colloquium
Friday, October 12, 2001
4:00 PM
Physics Building, Room 204
David F. Anderson [Host: Craig Dukes]
Fermi National Accelerator Laboratory
"Understanding Flight"
ABSTRACT:
Through the years the explanation of flight has become mired in misconceptions that have become dogma. Wolfgang Langewiesche, the author of "Stick and Rudder" (1944) got it right when he wrote: "Forget Bernoulli's Theorem". A wing develops lift by diverting (from above) a lot of air. This is the same way that a propeller produces thrust and a helicopter produces lift. Newton's three laws and a phenomenon called the Coanda effect explain most of it. With an understanding of the real physics of flight, many things become clear. Inverted flight, symmetric wings, and the flight of insects are obvious. It is easy to understand the power curve, high-speed stalls, and the effect of load and altitude on the power requirements for lift. The contribution of wing aspect ratio on the efficiency of a wing, and the true explanation of ground effect will also be discussed.
ics Colloquium
Friday, October 5, 2001
4:00 PM
Physics Building, Room 204
Arthur S. Brill [Host: E. Kolomeisky]
University of Virginia
"Hyperfine physics - from the hydrogen atom to hemoglobin"
ABSTRACT:
Hyperfine physics deals with interactions between electron and nuclear spins. Measurements of these interactions provide information about the electronic structure of paramagnetic sites in molecules and crystals. Examples will be presented and briefly discussed of the roles of such measurements in atomic, biological, condensed matter molecular and nuclear physics.
ics Colloquium
Friday, September 28, 2001
4:00 PM
Physics Building, Room 204
Krishna Rajagopal [Host: Peter Arnold]
MIT
"From the QCD Phase Diagram to Heavy Ion Collisions and Back"
ABSTRACT:
I describe some of the things we think we know about the physics of a hot quark-gluon plasma and the phase transition between the stuff of the big bang and ordinary hadronic matter. The questions I will pose motivate people to collide heavy ions at relativistic energies. I will give two examples of how we may use measurements made in these experiments to map the QCD phase diagram, and hence to study the condensed matter physics of QCD.
ics Colloquium
Friday, September 21, 2001
4:00 PM
Physics Building, Room 204
Jun Ye [Host: Thomas Gallagher]
JILA
"Light: Time meets frequency"
ics Colloquium
Friday, September 14, 2001
4:00 PM
Physics Building, Room 204
Puru Jena [Host: Lou Bloomfield and Joe Poon]
Virginia Commonwealth University , Richmond, VA - Department of Physics
"TheRole of Clusters in the Design of Nano-Scale Systems"
ABSTRACT:
Atomic clusters consisting of a few to a few thousand atoms constitute a new phase of matter intermediate between atoms and solids. Unlike conventional nanostructured materials, the size and composition of these clusters can be controlled one atom at a time. The properties of such clusters brought about by their large surface-to-volume ratio, unique geometry, low dimensionality and reduced coordination, exhibit novel behavior quite unlike that in the bulk. For example, metallic elements can be made to form ionic bonds while nonmagnetic and anti-ferromagnetic materials can become ferromagnetic or ferrimagnetic. This talk will introduce the principles for designing these clusters and discuss a concept where clusters can be viewed as super-atoms - adding a third dimension to the periodic table. Recent experimental evidence to support this idea will be presented. Examples of cluster assembled materials will include high-energetic materials involving Al(MnO4)3, alkali metal clusters isolated in zeolites, transition metal clusters supported on organic and metallic substrates, and manganese-oxide clusters passivated by acetate ligands. Ultimately the properties of crystals composed of clusters as the building blocks will be discussed. It is hoped that the synergy between theory and experiment will lead to the synthesis of cluster assembled materials with unique and tailored properties, thus creating new opportunities in materials science at the dawn of the new millennium.
ics Colloquium
Friday, September 7, 2001
4:00 PM
Physics Building, Room 204
J. Elkins [Host: T. Gallagher]
National Oceanic and Atmospheric Administration
"A Problem in Atmospheric physics: Stratospheric ozone depletion"
ABSTRACT:
Since 1987, almost all countries have signed the Montreal Protocol to control substances that cause depletion of the ozone layer. One of the successes of the Protocol has been the dramatic decrease in emissions of methyl chloroform, a metal degreaser that has been responsible for the decline of total equivalent chlorine in the atmosphere. However, chlorofluorocarbon (CFC-12), a common refrigerant, and the halons, fast-acting fire extinguishing agents, are still increasing in the atmosphere even though production ceased for the developed countries in 1996. This research talk will discuss ground-based and airborne measurements and their implication for the future ozone depletion. Preliminary results from a recent field campaign operated on the Trans-Siberian Railway will also be presented.
ics Special Colloquium-Please note special time
Friday, May 11, 2001
11:00 AM
Physics Building, Room 204
Professor James Stone [Host: Robert Jones]
Boston University and Department of Energy
"A Study of Atmospheric Neutrinos with the Super-Kamiokande Detector"
ABSTRACT:
The observation of flavor oscillations in atmospherically produced neutrinos by the Super-Kamiokande Experiment represents the first indication of massive neutrinos and new physics beyond the Standard Model of Particle Physics. Neutrino physics in the context of oscillations will be discussed and a detailed description of the Super-Kamiokande detector will be presented. The latest experimental results on proton decay, atmospheric and long baseline neutrino studies will be shown.
ics Colloquium
Friday, May 4, 2001
4:00 PM
Physics Building, Room 204
Dr. Jeff Appel [Host: Brad Cox]
Fermilab
"The Fixed-Target Charmed Road to Understanding Hadrons"
ABSTRACT:
Measurements involving charm quarks tell us about the nature and details of light hadrons. This talk will summarize how and what we are learning from charm fixed-target experiments about the usual ground-state hadrons, and about scalar resonances such as the sigma, kappa, and f_0's which have had uncertain histories so far.
ics Special Colloquium
Thursday, May 3, 2001
4:00 PM
Physics Building, Room 204
Pierre Pillet [Host: Thomas Gallagher]
Laboratoire Aime Cotton
"Formation and Trapping of Ultracold Molecules by Photoassociation"
ics Colloquium
Friday, April 27, 2001
4:00 PM
Physics Building, Room 204
Brian Cole [Host: C. Dukes]
Columbia University
"The Baryon Junction and High-Energy Nuclear Collisions"
ABSTRACT:
In the 1970's Veneziano suggested the existence of a set of diagrams in Regge theory that could allow the baryon number to be "extracted" from a baryon in a single step in high-energy hadronic interactions. Because no experimental evidence for these diagrams was found, the idea was largely forgotten. However, in recent years it has been resurrected and re-cast in terms of the so-called "baryon junction" a (possible) non-perturbative topological defect in the gluon fields within the baryon. In this picture, the junction plays the role of "bookkeeper" for baryon number conservation in high-energy collisions. Current theoretical models suggest that diagrams involving the exchange of the junction only become important in hadronic (e.g. p-p) collisions at collider energies. However, the junction may become active at much lower energies in nuclear collisions due to the multiple interaction of the incident nucleons. I will use results from a new generation of experiments studying proton-collisions at the Brookhaven National Laboratory AGS and CERN SPS accelerators to illustrate the possible role played by the junction in the "stopping" of the protons and in the abundant production of strange baryons and the production of anti-baryons. I will then discuss the possibility that the junction may be responsible for some of the anomolous results obtained from fixed-target heavy-ion experiments at the CERN SPS that were recently argued to provide evidence for quark-gluon plasma formation in high-energy nuclear collisions. I will discuss future studies of junction physics in fixed-target proton-nucleus experiments and in proton-proton and proton-nucleus collisions at the Relativistic Heavy Ion Collider. I will finish by highlighting some recent speculation that novel states of matter formed from "meshes" of junctions and anti-junctions may be created in heavy-ion collisions at RHIC.
ics Colloquium
Friday, April 20, 2001
4:00 PM
Physics Building, Room 204
Hank Thacker [Host: Joseph Poon]
University of Virginia
"How QCD Works"
ABSTRACT:
Mathematically, the interaction between quarks and gluons is remarkably similar to the electromagnetic interaction of electrons and photons. But unlike QED, QCD has an essentially nonperturbative structure, as exhibited most strikingly by the absolute confinement of quarks, which represents a fundamental property of the QCD vacuum (complete screening of color charge). Another property of QCD, chiral symmetry breaking, is also a statement about the vacuum, i.e. that it is full of quark-antiquark pairs (analogous to Cooper pairs in BCS theory). Chiral symmetry breaking and quark confinement are probably related phenomena, but the connection is poorly understood. I will discuss recent lattice calculations which have begun to expose the structure of the QCD vacuum.
ics Colloquium
Friday, March 30, 2001
4:00 PM
Physics Building, Room 204
Professor Hongxing Jiang [Host: E. Kolomeisky and J. Poon]
Kansas State
"III-Nitride Micro- and Nano-Structures and Devices"
ABSTRACT:
Advances in materials research and novel structure designs have brought the dimensions of photonic devices to the scales of the wavelength of the light they emit, transmit, and detect. In this realm, quantum nature of light dominates, enabling more efficient and fast devices. In this talk, the fabrication and optical studies of micron and wavelength-scale photonic structures, including micro-cavities and micro-size light emitters, based on III-nitride wide bandgap semiconductors will be presented. Our recent work on sub-micron photonic structures prepared by e-beam lithography and plasma etching will be discussed. Potential applications of III-nitride micro- and nano-photonics in efficient energy conversion and optical communications will be also be summarized.
ics Colloquium
Friday, March 23, 2001
4:00 PM
Physics Building, Room 204
William Wootters [Host: Olivier Pfister]
Williams College
"Quantum Entanglement as a Resource for Communication"
ABSTRACT:
Quantum mechanical objects can exhibit correlations with one another that are fundamentally at odds with the paradigm of classical physics; one says that the objects are "entangled." In the past few years, entanglement has come to be studied not only as a marvel of nature but also as a potential resource, particularly as a resource for certain unusual kinds of communication. This talk reviews three proposed communication schemes based on entanglement: (i) dense coding, which is the effective doubling of the information-carrying capacity of a quantum particle through prior entanglement with a particle at the receiving end; (ii) teleportation, in which a quantum state is transferred from one particle to another over a distance, apparently without traversing the intervening space; and (iii) the efficient pooling of classical data, in which separated participants arrive at a conclusion faster because they share entanglement. These three schemes highlight three distinct ways in which entanglement can enhance communication.
ics Colloquium
Friday, March 9, 2001
4:00 PM
Physics Building, Room 204
Evelyn Patterson [Host: Steve Thornton]
U. S. Air Force Academy
"Using the World Wide Web for Physics Teaching and Learning: Exploring Where Pedagogy and Technology Meet"
ABSTRACT:
The explosion of World Wide Web technology over the past several years has spurred the development of an ever-increasing number of web-based teaching and learning materials and techniques. Web technology is being used to support student-teacher, student-student, and teacher-teacher communications, often providing communications channels and possibilities not possible previously. At the same time, physics education research continues to provide more insight about how, why, and the extent to which our students do-- and don't-- learn physics. Can our research-based understanding of how students learn and the new unprecedented power of communications lead us to improved courses and programs? This talk will survey the spectrum of ways in which the web is being used by the physics education community to promote physics teaching and learning. It will also introduce and discuss a unique mix of pedagogy and the web technology, the "Just-in-Time Teaching" (JiTT) strategy, now being implemented by over 120 faculty at more than 60 institutions across the country and in Canada and Europe."
ics Colloquium
Friday, March 2, 2001
4:00 PM
Physics Building, Room 204
B. Lee Roberts [Host: Blaine Norum]
Boston University
"Recent news from the vacuum? The Muon g-2 Experiment at Brookhaven"
ABSTRACT:
Since the experiments of Stern and Gerlach, magnetic moments of "elementary" particles have been important in our quest to understand subatomic physics. A brief review of the history and foundations of this field will be given as an introduction to the muon g-2 experiment at the Brookhaven AGS. This experiment, E821, has recently reported a new result with a relative accuracy of 1.3 ppm, which is larger than the theoretical (Standard Model) value by 2.6 standard deviations. The physics context of this measurement, the experiment, and the analysis leading to this new result will be presented.
ics Colloquium
Friday, February 23, 2001
4:00 PM
Physics Building, Room 204
Jamie Nagle [Host: Simonetta Liuti]
Columbia University
"First results from the Relativistic Heavy Ion Collider"
ics Colloquium
Friday, February 16, 2001
4:00 PM
Physics Building, Room 204
Prof. Pulak Dutta [Host: Joseph Poon]
Northwestern Univ.
"Nanoscale ordering in soft materials near surfaces and interfaces"
ABSTRACT:
A material is 'soft' if its structure, and thus its properties, can change in response to very weak stimuli; hence the current interest in using soft materials for switching, sensing, etc. One way to induce structures that do not occur otherwise is with the help of a surface or interface. This talk will give some examples of the use of synchrotron radiation to look at how molecules self-organize near surfaces and soft-hard interfaces. Our studies of Langmuir monolayers (including their use as templates for inorganic nucleation), self-assembled films, and normal liquids near interfaces will be described.
ics Colloquium
Friday, February 9, 2001
4:00 PM
Physics Building, Room 204
Nilanga Liyanage [Host: Gordon Cates]
Jefferson Laboratory
"Neutron Spin Structure Function Measurements at Jefferson Lab"
ABSTRACT:
Spin structure functions provide basic information about the spin of the quark distributions inside the nucleon. Measurements at high energy laboratories have provided precision spin structure function data at low values of xbj. However, there is little precision data at low and moderate values of momentum transfer and high values of xbj . This is especially true for the neutron due to the absence of a free neutron target. Polarized ND3 , NH3 and 3He targets at Jefferson lab combined with its high-polarization continuous electron beam have provided the opportunity to make high precision neutron spin structure measurements in the high xbj region. As examples of high precision measurements possible at Jefferson lab, I will describe two planned neutron spin structure measurements, one in the deep inelastic region and the other in the resonance region, using the Hall A polarized 3He target. The deep inelastic measurement will provide the first precision test of predictions for the virtual photon asymmetry An1 in the valence quark region. The measurement in the resonance region, combined with the DIS measurement will provide a first test of quark-hadron duality for spin structure of the neutron
ics Colloquium
Thursday, February 8, 2001
4:00 PM
Physics Building, Room 204
Jun Ye [Host: T. Gallagher]
JILA
"TBA"
ics Joint Physics/Biology Colloquium
Friday, January 19, 2001
4:00 PM
Physics Building, Room 204
Alan McKane [Host: Tim Newman]
Department of Physics -University of Manchester, UK
"Ecological dynamics of multispecies communities"
ABSTRACT:
Many theoretical physicists with a background in non-equilibrium statistical mechanics are becoming interested in exploring mathematical models of ecosystems. The reason for this is clear when one realizes that such models typically involve a large number of individuals interacting according to simple rules and that the ultimate aim is to compute coarse-grained or long-time behavior. The ingredients of these models include population dynamics, predator-prey interactions, competitive effects, speciation and immigration. Two examples will be discussed. One is a model which describes the evolution of food webs using adaptive dynamics and the other, a stochastic model of species-rich ecosystems which makes predictions concerning the form of the species abundance distribution.
ics Colloquium
Friday, December 8, 2000
4:00 PM
Physics Building, Room 204
Prof. A T. Johnson, Jr. [Host: Joseph Poon]
Univ. of Pennsylvania
"Quantum Confinement of Electrons and Phonons in Single Wall Carbon Nanotubes"
ABSTRACT:
Single wall carbon nanotubes are a fascinating set of nanomaterials whose unique physical properties reflect the effect of quantum confinement on the electronic and phonon energy spectrum. Electron waves confined to the cylindrical tube wall obey periodic boundary conditions. Their energy spectrum consists of a set of one-dimentional subbands, making nanotubes metals or semiconductors depending on the precise wrapping of the constituent graphene sheet. I will discuss functional nanotube devices we have made, including field effect transistors, diodes, and highly conducting electrical interconnects. Nanotube sound waves (phonons) also experience quantum size effects. This makes nanotubes incredibly stiff, and may enable mechanical composites or nano-mechanical systems. We recently measured the effect of the quantized phonon spectrum on the specific heat of nanotubes as well as their thermal conductivity. Our results support theoretical predictions that nanotubes have an extremely high thermal conductivity, perhaps the highest of any known material.
ics Colloquium
Friday, November 10, 2000
4:00 PM
Physics Building, Room 204
Rick Trebino [Host: Louis Bloomfield]
Georgia Tech
"The Musical Score, the Fundamental Theorem of Algebra, and the Measurement"
ABSTRACT:
To measure an event in time requires a shorter one. As a result, the development of a technique to measure ultrashort laser pulses--less than 10-12 seconds long and the shortest events ever created--has been particularly difficult. We have, however, recently developed a simple method for fully characterizing these events, that is, for measuring a pulse's intensity and phase vs. time. This method relies on two seemingly unrelated ideas: the concept of the musical score and the fact that the Fundamental Theorem of Algebra fails in two dimensions. Specifically, an optical analog of a musical score of the pulse is produced by measuring its spectrogram. And the mathematics involved is equivalent to the two-dimensional phase-retrieval problem--a problem that is solvable only because the Fundamental Theorem of Algebra fails in two dimensions. We call the method Frequency-Resolved Optical Gating (FROG), and it is simple, rigorous, intuitive, and general. It can measure pulses in all spectral ranges, on a single-shot basis, and over a wide range of energies. FROG has been used to measure pulses as short as 4.5 femtoseconds (4.5 x 10-15 sec), and it can measure two pulses simultaneously. More recently, we have shown that FROG can be used in conjunction with spectral interferometry to measure essentially arbitrary pulses with as little as zeptojoules of energy (less than one photon!) on a multi-shot basis.
ics Colloquium
Friday, November 3, 2000
4:00 PM
Physics Building, Room 204
Margaret Murray [Host: Simonetta Liuti]
Department of Mathematics, Virginia Tech
"Women Becoming Mathematicians: The Doctoral Classes of 1940-1959"
ABSTRACT:
I give a report on an oral history-based study of the approximately 200 women who earned Ph.D.'s in mathematics from American colleges and universities during the years 1940-1959. I focus in some detail on the following questions: How did the women of this generation develop their mathematical interests and ambitions? Which individuals and institutions were particularly supportive of their mathematical goals? What obstacles to professional success did they encounter as they tried to build careers in mathematics? How did they balance the competing demands of career and personal life? How did they strike a balance between teaching, research, and service to the profession? What lessons can contemporary mathematicians, male and female, learn from the experiences of this generation?
ics Special Atomic Colloquium - Please note special time
Wednesday, November 1, 2000
4:00 PM
Physics Building, Room 204
Yanhua Shih [Host: O. Pfister]
Univ. of Maryland Baltimore County
"Quantum Entanglement and Quantum Teleportation"
ics Colloquium
Friday, October 27, 2000
4:00 PM
Physics Building, Room 204
Boris Kayser [Host: P.Q. Hung]
National Science Foundation
" Why do We Think Neutrinos Have Mass? And What's Next? "
ABSTRACT:
We explain why the evidence for nonzero neutrino masses is compelling. Then, we turn to the questions about neutrinos raised by the presence of their nonzero masses. These questions include: How many different neutrinos are there? How much do they weigh? Is each neutrino identical to its antiparticle? How will we answer questions like these?
ics Colloquium
Friday, October 20, 2000
4:00 PM
Physics Building, Room 204
Joe Thompson [Host: Shivaram]
LANL
"Superconductivity in a New Family of Heavy-Fermion Compounds"
ABSTRACT:
The discovery of superconductivity in CeCu2Si2 nearly 20 years ago was totally unexpected and contradicted fundamental tenants of the well-established BCS theory of superconductivity. Instead of the magnetic moment carried by Ce+3 suppressing superconductivity, as expected from BCS, the presence of Ce was essential for superconductivity and responsible for increasing the effective mass of the electrons participating in superconductivity by orders-of-magnitude-hence, heavy-fermion superconductivity. As we now know, CeCu2Si2 was the first example of superconductivity mediated by antiferromagnetic spin fluctuations, which also may be the dominant pairing mechanism in high-temperature superconductors, and other parallels between heavy-fermion and cuprate superconductivity are emerging. Recently, we have discovered a new family of heavy-fermion materials, CeMInsub5 (M=Rh, Co, and Ir), in which superconductivity appears at temperatures higher than in any other heavy-fermion system. These materials form in a quasi-2D structure, which makes an analogy with the cuprate's magnetism and superconductivity appealing. Though much remains to be learned about their properties, this new family appears to be quite interesting and provocative.
ics Colloquium
Friday, October 6, 2000
4:00 PM
Physics Building, Room 204
Professor Marvin Girardeau [Host: Eugene Kolomeisky]
University of Arizona
"Theory of de Broglie Waveguides"
ABSTRACT:
Several experimental groups have recently succeeded in constructing quasi-one-dimensional (1D) atom waveguides and loading them with Bose-Einstein condensates of ultracold atomic vapors. An important motivation for such studies is the goal of constructing atomic de Broglie wave beam splitters and interferometers for ultrasensitive detection of very weak accelerations and gravitational perturbations. This talk will discuss the many-body Schrodinger dynamics of 1D systems of impenetrable bosons, which is exactly soluble via an exact mapping from an ideal Fermi gas to a strongly interacting Bose gas of impenetrable point particles. After description of some completed work on such systems in 1D toroidal geometries and harmonic traps, some work in progress will be described, concerned with a generalization to a model of a de Broglie beam splitter/interferometer using two coupled waveguides.
ics Joint Astronomy-Physics Colloquium
Monday, October 2, 2000
4:00 PM
Astronomy Building, Room 201
Max Tegmark [Host: T. X. Thuan]
University of Pennsylvania - Physics Dept.
"Zeroing in on cosmological parameters"
ABSTRACT:
I describe the sharp constraints on cosmological paramaters placed by recent measurements of the cosmic microwave background, distant supernovae, galaxy clustering, etc., and how different types of measurements how allow powerful cross-checks to be made. I also comment on outstanding puzzles in the emerging cosmological "standard model" and upcoming measurements that may resolve them.
ics Colloquium
Friday, September 29, 2000
4:00 PM
Physics Building, Room 204
Richard Hughes [Host: Simonetta Liuti]
Los Alamos National Laboratories
"Quantum cryptography"
ABSTRACT:
Quantum cryptography, or more accurately quantum key distribution (QKD), uses single-photon transmissions to generate the shared, secret random number sequences, known as cryptographic keys, which are used to encrypt secret communications. Appealing features of QKD are that its security is based on principles of quantum physics and attempted eavesdropping can be detected. (Heisenberg’s uncertainty principle ensures that an adversary can neither successfully tap the key transmissions, nor evade detection because eavesdropping raises the key error rate above a threshold value). I shall describe two quantum cryptography systems, based on the transmission of non-orthogonal single-photon states to generate shared key material, at Los Alamos. In one experiment we are generating key material over a 48-kilometer optical fiber path, and in the other by transmitting photons over a 1.6-km atmospheric path in daylight. In both cases, key material is built up using the transmission of a single-photon per bit of an initial secret random sequence. A quantum-mechanically random subset of this sequence is identified, becoming the key material after a data reconciliation stage with the sender. The atmospheric results show that QKD could be used for surface to satellite transmissions.
ics Colloquium
Friday, September 22, 2000
4:00 PM
Physics Building, Room 204
Laszlo Tisza [Host: Vittorio Celli]
MIT
"History of the two-fluid model and Bose-Einstein condensation"
ics Colloquium
Friday, September 15, 2000
4:00 PM
Physics Building, Room 204
Professor Subir Sachdev [Host: Eugene Kolomeisky]
Yale University
" Quantum criticality in the high temperature superconductors"
ABSTRACT:
I discuss the phases and critical points of quantum antiferromagnets in two dimensions and their relationship to the physical properties of the high temperature superconductors. Non-magnetic impurities are argued to be a sensitive probe of the wavefunction of the electron spins: I will describe recent experiments on such impurities and the theoretical insights they have provided on the interplay of antiferromagnetism and superconductivity.
ics Joint Chemistry/Physics Colloquium
Friday, September 1, 2000
4:00 PM
Chemistry Building, Room 304
Shaul Mukamel [Host: Ian Harrison]
University of Rochester - Chemistry Dept.
"Collective excitations and Multidimensional optical spectroscopies of dendrimers and biomolecules"
ics Joint Physics and Engineering Physics Colloquium
Friday, April 28, 2000
4:00 PM
Physics Building, Room 204
Joel Fajans [Host: J. Dorning/Joseph Poon]
University of California at Berkely
"Pure-Electron Plasma Experiments"
ABSTRACT:
Plasmas made only of electrons are remarkably stable and manipulatable. They are ideal for studying basic plasma physics, two-dimensional fluid dynamics, and nonlinear dynamics. I will discuss some basic plasma results, including a demonstration that like charges can attract rather than repel, and that sometimes mountaintops are just as stable as valley floors. Next I will describe some fluid results like the instability shown in the figure below. Finally I will discuss autoresonance, a very basic and general phenomenon which occurs in nonlinear oscillator systems.
ics Colloquium
Friday, April 14, 2000
4:00 PM
Physics Building, Room 204
Eugene Kolomeisky [Host: Joseph Poon]
University of Virginia
"Superfluidity in low dimensions: beyond the mean-field theory"
ABSTRACT:
The Gross-Pitaevskii approximation is a long-wavelength theory widely used to describe a variety of properties of dilute Bose condensates, in particular trapped alkali gases. In this talk I will show that for short-ranged repulsive interactions this theory fails in one and two spatial dimensions, and appropriate low-dimensional modifications will be proposed. The new theory has a universal character, and some of its implications such as density profiles in confining potentials, superfluidity, solitons, and self-similar solutions will be discussed.
ics Colloquium
Friday, March 31, 2000
4:00 PM
Physics Building, Room 204
E. Fischbach [Host: Rogers Ritter]
Purdue University
"The Search for Non-Newtonian Gravity"
ABSTRACT:
Ongoing attempts to unify the known fundamental forces lead to the suggestion that there may exist new gravity-like forces in nature. These would arise from the exchange of new light bosonic quanta among the constituents of ordinary matter, and would produce apparent deviations from the predictions of Newtonian gravity. The suggestion of such a "fifth force" in 1986 has led to a broadened view of the interaction of gravity and other known and hypothetical forces, and has helped to stimulate a large number of new experiments to search for weak long-range forces. This talk will review both the theoretical motivation for such new forces, and the experimental results that have been obtained to date. More recently newer string-inspired theories have suggested the presence of additional macroscopic forces acting over sub-millimeter distances. Detecting such forces presents special challenges-both theoretical and experimental- for reasons that I will discuss.
ics SPECIAL COLLOQUIUM
Friday, March 24, 2000
4:00 PM
Physics Building, Room 204
Yongsheng Gao [Host: Brad Cox]
Harvard University
"On the road to measure CP violation and test the Standard Model:Observation of hadronic b --> u transitions"
ABSTRACT:
CP violation is one of the great mystery of the universe. The major motivation of the first-generation B factories is to measure CP violations in the B meson system, especially the three CKM angles Alpha, Beta and Gamma. I'll present the first observation of hadronic b --> u transitions (B --> Pi+Rho-, Pi+Rho0, Pi+Pi-) which will be very important for the future measurements of the CKM angles Alpha and Gamma. Measuring Alpha and Gamma using these decay modes at the first-generation B factories will be discussed, along with a future outlook of B physics
ics Colloquium
Friday, March 17, 2000
4:00 PM
Physics Building, Room 204
Prof. Gerassimos (Makis) Petratos [Host: Oscar Rondon]
Kent State University
"Elastic Electron Deuteron Scattering: Past, Present and Future"
ABSTRACT:
This talk will present a review of elastic electron scattering off the simplest nucleus, the deuteron. The elastic scattering process has long been a crucial tool in understanding the internal structure and dynamics of the nuclear two-body system. Studies of the deuteron form factors, measured in elastic scattering, offer unique opportunities to test both the conventional meson-nucleon "standard model" that describes the deuteron electromagnetic structure, and "nuclear chromodynamics" predictions of perturbative Quantum Chromodynamics based on the underlying quark-gluon substructure of the deuteron. A review of both the theoretical framework and of past (SLAC) and recent (JLab) measurements of the deuteron form factors will be presented
ics Colloquium
Friday, March 10, 2000
4:00 PM
Physics Building, Room 204
Eric Zimmerman [Host: Brad Cox]
Columbia University
"Searching for new particles in a high-energy neutrino beam: New results from Fermilab"
ics Colloquium
Friday, March 3, 2000
4:00 PM
Physics Building, Room 204
Roger Chevalier [Host: P. Q. Hung]
University of Virginia
"Supernova - Gamma Ray Burst Connection"
ics Colloquium
Friday, February 25, 2000
4:00 PM
Physics Building, Room 204
Takeshi Egami [Host: Despina Louca]
University of Pennsylvania
"Dealing with Regional Conflict: Spin-Charge Inhomogeneity in Superconducting Cuprates and CMR Manganites."
ABSTRACT:
The discovery of high-temperature superconductivity was a double shock to the condensed matter physics community. Not only the critical temperature was so outrageously high (until then 30 K was considered to be the theoretical maximum), but magnetism appeared to be intimately involved, while for a long time magnetism had been considered to be incompatible with superconductivity. It then became the holy grail of theoreticians to overcome this apparent paradox, and various high-wire-act theories have been proposed. In the meantime, experimental data are accumulating that suggest a more conventional method of avoiding regional conflict between the spin and charge, by segregation. However, just as the social and international problems complete segregation simply defers the problem and does not solve it. Oxides are far ahead of us, and appear to have reached an intelligent solution. We discuss the results of recent inelastic and elastic neutron scattering measurements on cuprates and manganites, and speculate what this solution might be.
ics Colloquium
Friday, February 18, 2000
4:00 PM
Physics Building, Room 204
Paul Fendley [Host: Joseph Poon]
Univerisy of Virginia - Physics
"The Observation of Fractional Charge"
ics Colloquium
Friday, February 4, 2000
4:00 PM
Physics Building, Room 204
Eugene Kolomeisky [Host: Joseph Poon]
University of Virginia
"Breaking a one-dimensional chain: fracture in 1 + 1 dimensions"
ABSTRACT:
The breaking rate of an atomic chain stretched at zero temperature by a constant force can be calculated in a quasiclassical approximation by finding the localized solutions ("bounces") of the equations of classical dynamics in imaginary time. We show that this theory is related to the critical cracks of stressed solids, because the world lines of the atoms in the chain form a two-dimensional crystal, and the bounce is a crack configuration in (unstable) mechanical equilibrium. Thus the tunneling time, Action, and the breaking rate in the limit of small forces are determined by the classical results of Griffith. For the limit of large forces we give an exact bounce solution that describes the quantum fracture and classical crack close to the limit of mechanical stability. This limit can be viewed as a critical phenomenon for which we establish a Levanyuk-Ginzburg criterion of weakness of fluctuations, and propose a scaling argument for the critical regime. The post-tunneling dynamics is understood by the analytic continuation of the bounce solutions to real time.
ics Colloquium
Friday, January 28, 2000
4:00 PM
Physics Building, Room 204
Robert Hull [Host: Joseph Poon]
Dept. Materials Science and Engineering, UVA
"New Techniques For Nanoscale Fabrication And Characterization"
ABSTRACT:
The gallium focused ion beam produces highly collimated (10 nm - 1(mu)m) beams of high energy (3 - 30 kV) ions. These beams may be used as nanoscale “scalpels” to micromachine virtually any material by direct sputtering of the target surface. Combined with ion-beam induced deposition from organic vapors, this provides unique capabilities for sub 100 nm fabrication of three dimensional structures. I will describe how these capabilities form the basis of a new “nanoprinting” technology, for deep sub-micron pattern definition over planar and curved surfaces. In addition, imaging and spectroscopy in the focused ion beam system enables new routes for three-dimensional characterization and visualization of microscale structures. During sputtering by the primary beam, large numbers of secondary electrons and ions are produced, which may be used to form images of the sputtered surface. By concatenating images of surfaces at different depths during the sputtering process, three-dimensional reconstructions of the structure may be generated. These reconstructions can contain up to 107 independent pixels of information. Furthermore, using a quadrupole mass spectrometer, element-specific images may be obtained. These techniques enable “miroscopy in the third dimension” which can be of immediate and powerful impact in understanding material microstructure.
ics Colloquium
Friday, December 3, 1999
4:00 PM
Physics Building, Room 204
Prof. Sid Redner [Host: E. Kolomeisky]
Boston University
"Aggregation Kinetics in Gelation, Traffic, Wealth, and other Everyday Phenomena"
ABSTRACT:
In aggregation, clusters meet and irreversibly merge so that their average size grows continuously with time. This process describes, for example, making of jello and yogurt, raindrop formation in clouds, and the mass distribution of stars. I will present an elementary overview of cluster evolution in such aggregating systems. I begin by outlining the mean-field theory of aggregation and showing how scaling provides basic insights into long-time behavior. I will then discuss the intriguing relation between the cluster-size distribution and the first-passage probability of a random walk. Finally, I will discuss recent applications to traffic clustering and the distribution of wealth.
ics Colloquium
Friday, November 19, 1999
4:00 PM
Physics Building, Room 204
Jim Stone [Host: Craig Dukes]
Boston University/Department of Energy
"Neutrino Mass--Experimental Results from Super-Kamiokande"
ics Colloquium
Friday, November 12, 1999
4:00 PM
Physics Building, Room 204
Professor Ctirad Uher [Host: Joseph Poon]
University of Michigan
"Materials with Open Structures as Novel Thermoelectrics"
ics Colloquium
Friday, November 5, 1999
4:00 PM
Physics Building, Room 204
David Spergel [Host: Peter Arnold]
Princeton University
"Cosmic Microwave Background Fluctuations: A Probe of Cosmology"
ABSTRACT:
Observations of the microwave background are a powerful probe of the physics of the early universe and of cosmological parameters. Over the past few years, there has been a dramatic improvement in the quality of data. The current observations are consistent with a flat universe with a cosmological constant in which inflation produced the primordial fluctuations. Next year, NASA plans to launch MAP, a satellite that will make precision measurements of microwave background fluctuations. With these measurements, we will be able to test our basic cosmological paradigm. If correct, we can then use these observations to measure the basic cosmological parameters to high precision.
ics Colloquium
Friday, October 29, 1999
4:00 PM
Physics Building, Room 204
Alwyn Wootten [Host: Bascom Deaver]
National Radio Astronomy Observatory
"The Atacama Large Millimeter Array: Imaging Cosmic Dawns"
ABSTRACT:
The Atacama Large Millimeter Array (ALMA), a project of the National Radio Astronomy Observatory and the European Southern Observatory, will be built over the coming decade in Northern Chile. ALMA will be a revolutionary telescope, operating at millimeter and submillimeter wavelengths and comprised of an array of individual antennas each 12 meters in diameter that work together to make precision images of astronomical objects. The goal of the ALMA Project is an array of 64 antennas that can be positioned as needed over an area 10 kilometers in diameter so as to give the array a zoom-lens capability. ALMA will image the universe with unprecedented sensitivity and sharpness at millimeter and submillimeter wavelengths. The energy density of radiation from both the Milky Way and from the diffuse extragalactic background peaks in the submillimeter. Aside from Cosmic Microwave Background photons, submillimeter photons are the most abundant photons in the Universe. Detailed imaging at these wavelengths will be a major step for astronomy, making it possible to study the origins of galaxies, stars and planets.
Colloquia and Special Lectures Committee
Brad Cox (Chair)
P.Q. Hung (Member)
Israel Klich (Member)
Seunghun Lee (Member)
Peter Schauss (Member)
Jeffrey Teo (Member)
Marija Vucelja (Member)

To add a speaker, send an email to bbc2x@Virginia.EDU Include the seminar type (e.g. Colloquia), date, name of the speaker, title of talk, and an abstract (if available). [Please send a copy of the email to phys-speakers@Virginia.EDU.]