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Atomic Physics Seminars This Term

ics Atomic
Monday, September 2, 2019
4:00 PM
Physics Building, Room 204
Available
ics Atomic
Monday, September 9, 2019
4:00 PM
Physics Building, Room 204
Available
ics Atomic
Monday, September 16, 2019
4:00 PM
Physics Building, Room 204
RESERVED
ics Atomic
Monday, September 23, 2019
4:00 PM
Physics Building, Room 204
Available
ics Atomic
Monday, September 30, 2019
4:00 PM
Physics Building, Room 204
Available
ics Atomic
Monday, October 7, 2019
4:00 PM
Physics Building, Room 204
Available
ics Atomic
Monday, October 14, 2019
4:00 PM
Physics Building, Room 204
RESERVED
ics Atomic
Monday, October 21, 2019
4:00 PM
Physics Building, Room 204
Dmitry Green [Host: Peter Schauss]
AppliedTQC.com, ResearchPULSE LLC
"Path to building quantum spin liquids and topological qubits within existing quantum hardware"
 
 Slideshow (PDF)
ABSTRACT:

We address a central problem in the creation and manipulation of quantum states: how to build topological quantum spin liquids with physically accessible interactions. Theorists have been studying models of quantum spin liquids that rely on "multi-spin" interactions since the 1970s, and, more recently, have realized that these models can be used for quantum computing. However, nature does not provide such interactions in real materials. We construct a lattice gauge model where the required, fully quantum, multi-spin interactions can in fact be emulated exactly in any system with only two-body Ising interactions plus a uniform transverse field. The latter systems do exist. Therefore, our solution is an alternative path to building a workable topological quantum computer within existing hardware.  Our bottom-up construction is generalizable to other  gauge-like  theories,  including  those  with  fractonic  topological  order  such  as the  X-cube model. Taken as a whole, our approach is a blueprint to emulate topologically ordered quantum spin liquids in programmable quantum machines.

SLIDESHOW:
ics Atomic
Monday, October 28, 2019
3:30 PM
Physics Building, Room 204
Note special time.
Alexey Gorshkov [Host: Peter Schuass]
Joint Quantum Institute/University of Maryland
"Dynamics of quantum systems with long-range interactions"
ABSTRACT:

Atomic, molecular, and optical systems often exhibit long-range interactions, which decay with distance r as a power law 1/r^alpha. In this talk, we will derive bounds on how quickly quantum information can propagate in such systems. We will then discuss applications of these bounds to numerous phenomena including classical and quantum simulation of quantum systems, prethermal phases in Floquet systems, entanglement area laws, sampling complexity, and scrambling.

ics Atomic
Thursday, October 31, 2019
11:00 AM
Physics Building, Room 204
Note special date.
Note special time.
John Guthrie [Host: Cass Sackett]
Colorado State University
"Off-resonant RF Heating of Ultracold Plasmas to Measure Collision Rates "
ABSTRACT:

Ultracold plasmas provide us an opportunity to study exotic plasma regimes on a table-top laboratory scale. In particular, we can explore parameter spaces where strong coupling and electron magnetization effects play an important role like in some fusion and astrophysical systems. We have developed a new technique to measure electron-ion collision rates in ultracold plasmas using off-resonant RF heating of the electrons. By using the known variation in photoionization energy with photoionization laser wavelength and applying controlled sequences of electric fields, the amount of heating imparted can be calibrated and precisely measured. This allows the comparison of electron-ion collision rates as a function of plasma parameters such as electron temperature/degree of strong coupling and magnetization. A description of this technique and the experimental results obtained with it will be presented.

ics Atomic
Monday, November 4, 2019
4:00 PM
Physics Building, Room 204
Raman Chandra [Host: Peter Schauss]
Georgia Tech
"Quantum spins in space: the rich phases of spinor Bose gases"
ABSTRACT:

Many-body quantum systems have come under intense focus in recent years to enable a number of quantum simulation and sensing tasks.  Neutral atoms, ions and solid state qubits have all emerged as key platforms for inquiry.  One key set of questions concerns the ability of these delicately tailored quantum systems to relax to equilibrium when they are isolated from the environment, and whether such dynamics might have universal features.  Research in our laboratory on magnetic quantum fluids comprised of spin-1 Bose-Einstein condensed atoms (BECs) has a remarkable potential to address this problem.  In this talk I will show data from our lab demonstrating the rich interplay between many actors--magnetic interactions between spins, the influence of external magnetic fields, and the spatial quantum dynamics of many interacting modes that all compete to determine the non-equilibrium behavior.

 

Dr. Raman Biosketch:  Dr Chandra Raman is Associate Professor in the School of Physics at Georgia Tech where he performs experimental research on ultracold atomic gases and builds miniature atomic systems for quantum sensing applications. His work aims to understand the basic physics of complex quantum systems to harness them for applications. His group at Georgia Tech has uncovered new properties of quantized vortices, spin textures and quantum phase transitions in ultracold Bose gases, work for which he was awarded Fellowship in the American Physical Society in 2013. From 2013-15 he took a leave of absence to work in industry to better understand real world atomic sensors, work which he has translated into his laboratory today. 

ics Atomic
Monday, November 11, 2019
4:00 PM
Physics Building, Room 204
Norbert Linke [Host: Peter Schauss]
Joint Quantum Institute/University of Maryland
"Quantum-classical hybrid algorithms with trapped ions"
 
 Slideshow (PDF)
ABSTRACT:

We present results from a programmable quantum computer comprised of a chain of individually trapped 171Yb+ ions. It features individual laser beam addressing and individual readout, and can be configured to run any sequence of single- and two-qubit gates [1]. We combine this setup with different classical optimization routines to implement a so-called hybrid system. Quantum-classical hybrid protocols offer a path towards the application of near-term quantum computers for different optimization tasks. They are attractive since part of the effort is outsourced to a classical machine resulting in shallower and narrower quantum circuits, which can be executed with lower error rates.
We have realized several experimental demonstrations relating to this approach, such as the training of shallow circuits for Generative Modeling using a Bayesian optimization routine [2], tackling the Max-Cut problem using the Quantum Approximate Optimization Algorithm (QAOA) [3], and the preparation of thermal quantum states [4].
Recent results, limitations of the above methods, and ideas for boosting these concepts for scaling up the quantum-classical hybrid architecture will be discussed.
[1] S. Debnath et al., Nature 563:63 (2016); [2] D. Zhu et al., Science Advances 5, 10 (2019); [3] O. Shehab et al., arXiv:1906.00476 (2019); [4] D. Zhu et al., arXiv:1906.02699 (2019)

SLIDESHOW:
ics Atomic
Monday, November 18, 2019
4:00 PM
Physics Building, Room 204
Scott Smale [Host: Cass Sackett]
University of Toronto
"Dynamical phases and transitions in an ultracold Fermi gas"
ABSTRACT:

Non-equilibrium systems are ubiquitous in nature. They are actively studied in a wide range of fields, from biological cell membranes to city traffic planning. For the past several years our lab has been studying the dynamics of non-equilibrium ultracold degenerate Fermi gasses. We probe the dynamics via fast radio-frequency pulses enabled by trapping the atoms close to a microfabricated chip. The kinds of dynamics we have probed include the diffusion of spin in a strongly interacting Fermi gas, the rise of correlations in the gas after a quench of the interaction strength, and the phase transition between two different dynamical phases. Dynamical phases and the transitions between them are one possible framework to extend the powerful ideas of equilibrium statistical mechanics to diverse non-equilibrium systems. In my talk I will discuss our work on dynamics, focussing on our recent observation of dynamical phase transitions in the collective Heisenberg spin model.

ics Atomic
Monday, November 25, 2019
4:00 PM
Physics Building, Room 204
Available
ics Atomic
Monday, December 2, 2019
4:00 PM
Physics Building, Room 204
Available
Atomic Physics Seminars
Peter Schauss (Chair)

To add a speaker, send an email to ps5nw@Virginia.EDU Include the seminar type (e.g. Atomic Physics Seminars), 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.]