Colloquia This Term

ics Colloquium
Friday, August 31, 2018
3:30 PM
Physics Building, Room 204
Please See Condensed Matter Seminar Schedule
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, September 14, 2018
3:30 PM
Physics Building, Room 204

"Available"
ics Colloquium
Friday, September 21, 2018
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Monday, September 24, 2018
3:30 PM
Physics Building, Room 203
Note special date.
Note special room.
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 28, 2018
3:30 PM
Physics Building, Room 204
Roxanne Springer [Host: Simonetta Liuti]
Duke University
"Feynman╩╝s 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
Thursday, October 4, 2018
3:30 PM
Physics Building, Room 204
Note special date.
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, 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
Friday, October 12, 2018
3:30 PM
Physics Building, Room 204
Available
ics Colloquium
Friday, October 19, 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, November 2, 2018
3:30 PM
Physics Building, Room 204
Markus Diefenthaler [Host: Simonetta Liuti]
Jefferson Laboratory
"TBA"
ics Colloquium
Friday, November 9, 2018
3:30 PM
Physics Building, Room 204
Marija Vucelja [Host: Bob Jones]
UVA-Physics
"TBA"
ics Colloquium
Friday, November 16, 2018
3:30 PM
Physics Building, Room 204
Mark Stiles [Host: Joe Poon & Avik Ghosh]
NIST
"TBA"
ics Colloquium
Friday, November 30, 2018
3:30 PM
Physics Building, Room 204
Valery Nesvizhevsky [Host: Stefan Baessler]
Institut Laue Langevin, France
"TBA"
ics Colloquium
Friday, December 7, 2018
3:30 PM
Physics Building, Room 204
Zohar Komargodski [Host: Marija Vucelja]
Stony Brook University
"TBA"

To add a speaker, send an email to cas8m@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.]