Bulletin of the American Physical Society
50th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics APS Meeting
Volume 64, Number 4
Monday–Friday, May 27–31, 2019; Milwaukee, Wisconsin
Session P05: Many-Body Lattice Physics |
Hide Abstracts |
Chair: David Weld, University of California, Santa Barbara Room: Wisconsin Center 102C |
Thursday, May 30, 2019 10:30AM - 10:42AM |
P05.00001: Space-time Crystal and Space-time group Congjun Wu, Shenglong Xu Crystal structures and the Bloch theorem play a fundamental role in condensed matter physics. We extend the static crystal to the dynamic "space-time" crystal characterized by the general intertwined space-time periodicities in D+1 dimensions, which include both the static crystal and the Floquet crystal as special cases. A new group structure dubbed "space-time" group is constructed to describe the discrete symmetries of space-time crystal. Compared to space and magnetic groups, space-time group is augmented by "time-screw" rotations and "time-glide" reflections involving fractional translations along the time direction. A complete classification of the 13 space-time groups in 1+1D is performed. The Kramers-type degeneracy can arise from the glide time-reversal symmetry without the half-integer spinor structure, which constrains the winding number patterns of spectral dispersions. In 2+1D, non-symmorphic space-time symmetries enforce spectral degeneracies, leading to protected Floquet semi-metal states. Our work provides a general framework for further studying topological properties of the D+1 dimensional space-time crystal. [Preview Abstract] |
Thursday, May 30, 2019 10:42AM - 10:54AM |
P05.00002: Phasonic spectroscopy in a tunable quasicrystalline optical lattice Shankari Rajagopal, Toshihiko Shimasaki, Peter Dotti, Ruwan Senaratne, David Weld We describe studies of excitations in a tunable quantum quasicrystal realized using neutral strontium atoms in a bichromatic optical lattice. The phasonic degrees of freedom of solid-state quasicrystals are thought to have significant effects on thermal and electronic transport, yet are typically not dynamically accessible. Driving such a phason mode in a cold-atom context has revealed high-order multiphoton excitation processes, drawing a link to high-harmonic generation processes in solids. We study the dependence of these multiphoton processes on tunneling and modulation strength, and use the phasonic drive as a novel spectroscopic probe of the quasicrystal. Extensions to this work include realizing a phasonic Thouless pump, directly mapping out a slice of the Hofstadter butterfly spectrum, and studying effects of Anderson localization and mobility edges on interband transitions. [Preview Abstract] |
Thursday, May 30, 2019 10:54AM - 11:06AM |
P05.00003: Signatures of Mott and Anderson transitions in the quench dynamics of disordered fermions W. Morong, B. DeMarco We report disorder-induced transitions in the relaxation time of a system of strongly-interacting lattice fermions. The population of double occupancies is monitored following an interaction quench, and the re-equilibration time is found to vary strongly and non-monotonically as disorder is added. The resulting relaxation regimes are shown to correspond to predicted Mott insulator$-$correlated metal$-$Anderson-Mott insulator transitions for the ground state at half-filling. This allows for qualitative understanding of the quench dynamics, and shows the ability of relaxation measurements to sensitively probe changes in the density of states. [Preview Abstract] |
Thursday, May 30, 2019 11:06AM - 11:18AM |
P05.00004: Quantum many-body scarring: weak ergodicity breaking in an interacting Rydberg atom array simulator Wen Wei Ho, Soonwon Choi, Christopher Turner, Hannes Pichler, Alexios Michailidis, Zlatko Papic, Maksym Serbyn, Mikhail Lukin, Dmitry Abanin A central postulate of statistical mechanics is that of ergodicity -- a generic state prepared out of equilibrium is believed to explore its allowed phase phase and eventually thermalize. Recently, quench experiments in an interacting Rydberg atom array [Nature 551, 579 (2017)] demonstrated interesting nonequilibrium dynamics of a new kind: surprising periodic revivals and a lack of thermalization from certain simple initial states, while quick relaxation and equilibriation from others. Here we show that these observations are attributed to the presence of a small number of exceptional, nonthermal many-body eigenstates dubbed ``quantum many-body scars" that violate the eigenstate thermalization hypothesis. Furthermore, underlying this behavior is an isolated periodic orbit captured in a suitable ``semiclassical" analysis using matrix product states, which suggest a connection to scars in single-particle chaotic systems. Lastly we present work uncovering a nearby parent Hamiltonian that hosts perfect many-body scars, and construct a toy model with similar phenomenology. Quantum many-body scarring represents a new class of quantum dynamics in strongly interacting systems resulting from a weak form of ergodicity breaking, with direct experimental signatures. [Preview Abstract] |
Thursday, May 30, 2019 11:18AM - 11:30AM |
P05.00005: Does a distinct quasi many-body localized phase exist? A numerical study of a translationally invariant system in the thermodynamic limit Jesko Sirker We consider a quench in an infinite spin ladder describing a system with two species of bosons in the limit of strong interactions. If the heavy bosonic species has infinite mass the model becomes a spin chain with quenched binary disorder which shows true Anderson localization (AL) or many-body localization (MBL). For finite hopping amplitude J′ of the heavy particles, on the other hand, we find an exponential polarization decay with a relaxation rate which depends monotonically on J′. Furthermore, the entanglement entropy changes from a constant (AL) or logarithmic (MBL) scaling in time t for J′=0 to a sub-ballistic power-law, Sent∼tα with α<1, for finite J′. We do not find a distinct regime in time where the dynamics for J′≠0 shows the characteristics of an MBL phase. Instead, we discover a time regime with distinct dephasing and entanglement times, different both from a localized and a fully ergodic phase. [Preview Abstract] |
Thursday, May 30, 2019 11:30AM - 11:42AM |
P05.00006: ABSTRACT WITHDRAWN |
Thursday, May 30, 2019 11:42AM - 11:54AM |
P05.00007: Photoemission spectroscopy of a Fermi-Hubbard system with a quantum gas microscope Peter T. Brown, Elmer Guardado-Sanchez, Benjamin M. Spar, Waseem S. Bakr Strongly correlated systems with superconducting ground states, including the high-temperature superconducting cuprates and the unitary fermi gas, exhibit normal state precursors to the superconducting gap in their single-particle excitations. A quantitative understanding of these so called pseudogap regimes may elucidate details about the superconducting ground states, but developing this is difficult in real materials partly because the parameters of the microscopic Hamiltonian are not known. In cold atom experiments the development of fermionic quantum gas microscopes has enabled high-precision studies of fermions in optical lattices. The Hamiltonian parameters of these systems can be calculated from first principles, and consequently good agreement between theory and experiment has been reported in recent studies of equal-time spin and density correlations. In this talk I will report on the development of angle-resolved photoemission spectroscopy (ARPES) compatible with quantum gas microscopy and its application to studying pseudogap physics in an attractive Fermi-Hubbard system across the BEC-BCS crossover, setting the stage for future studies of the pseudogap regime in repulsive Hubbard systems. [Preview Abstract] |
Thursday, May 30, 2019 11:54AM - 12:06PM |
P05.00008: Dynamic Dopant Delocalization in a Hubbard Antiferromagnet Geoffrey Ji, Christie Chiu, Muqing Xu, Justus Brüggenjürgen, Annabelle Bohrdt, Michael Knap, Eugene Demler, Fabian Grusdt, Daniel Greif, Markus Greiner The interplay between spin and charge underlies much of the phenomena of the doped Hubbard model. Quantum simulation of the Hubbard model using quantum gas microscopy offers site-resolved readout and manipulation, enabling detailed exploration of the relationship between the two. We use this platform to explore spin and charge dynamics upon the delocalization of an initially-pinned hole dopant. We first prepare a two-component quantum gas of Lithium-6 loaded into a square optical lattice at half-filling and strong interactions, where the atoms exhibit antiferromagnetic spin ordering. During the loading process, we use a digital micromirror device to pin a localized hole dopant into the antiferromagnet. We then release the dopant and examine how it interacts with and scrambles the surrounding spin environment. The microscopic dynamics of dopants may provide further insight into the phases that appear in the doped Hubbard model. [Preview Abstract] |
Thursday, May 30, 2019 12:06PM - 12:18PM |
P05.00009: Many-body effects in momentum-space lattices Fangzhao An, Eric Meier, Bryce Gadway Nonlinear interactions, when added to a tight-binding lattice system, can result in many interesting phenomena. The physics of such a lattice model can be described in terms of a bosonic Josephson junction array, allowing for the study of phenomena similar to those found in tunnel-coupled superconductors. Using a lattice made of coupled momentum states, we show measurements progressing towards the full Josephson array. By tuning the effective interaction strength, we observe the onset of self-trapping in a one-dimensional lattice, and further show collective Bloch oscillations on a tilted array. [Preview Abstract] |
Thursday, May 30, 2019 12:18PM - 12:30PM |
P05.00010: Floquet Band Engineering of Ultracold Lithium in Driven Optical Lattices Ethan Simmons, Cora Fujiwara, Kevin Singh, Roshan Sajjad, David Weld Ultracold neutral atoms in driven optical lattices provide a rich experimental platform for probing non-equilibrium quantum dynamics. We report on the use of position-space Bloch oscillations to experimentally map out the Floquet-Bloch quasienergy band structure of a driven optical lattice. We present results of Floquet-engineered control of long-range transport, and discuss the use of multi-frequency driving to create novel states of matter. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700