Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session F33: Quantum Simulation IFocus Recordings Available

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Sponsoring Units: DAMOP Chair: Eduardo Ibarra Garcia Padilla, Rice Univ Room: McCormick Place W192C 
Tuesday, March 15, 2022 8:00AM  8:12AM 
F33.00001: Interacting Quantum Matter with Rydbergatom Synthetic Dimensions Sohail Dasgupta, Kaden R Hazzard Synthetic dimension platforms offer new unique ways of exploring quantum matter. Building on the recent success from collaborators in building a synthetic lattice of six Rydberg states on a single atom using ultracold ^{84}Sr atoms (arXiv:2101.02871), we study the manybody physics that occurs when atoms with internal synthetic lattices are loaded in microtraps. These interact via strong dipoledipole flipflop interactions, giving rise to a novel system exhibiting unique properties. Theoretical studies on a special case of this system, with equal synthetic tunnelings and uniform nearest neighbor flipflop interactions between adjacent synthetic sites, reveal phase transition into stringlike states for certain interaction strengths. With the synthetic dimension build from Rydberg states, the interactions are nonlocal and sitedependent. In this talk, we discuss the ground state and finite temperature properties of this system. We also discuss possibilities of exploring other kinds of systems with this platform such as having a different tunneling scheme in the synthetic dimension. 
Tuesday, March 15, 2022 8:12AM  8:24AM 
F33.00002: A hyperspherical approach to dipolar droplets Eli J Halperin, John L Bohn We apply a hyperspherical formulation to a dipolar BoseEinstein condensate. Central to this approach is a general correspondence between Kharmonic hyperspherical methods and a suitable Gaussian ansatz to the GrossPitaevskii equation, regardless of the form of the interparticle potential. In the case of the dipolar BoseEinstein condensate, this motivates the inclusion of a beyondmean field term within the hyperspherical picture, which allows us to describe the energies and wavefunctions of excitations of selfbound dipolar droplets outside of the meanfield limit. This approach provides a regime for exploring transitions between the liquid and gas phases. 
Tuesday, March 15, 2022 8:24AM  8:36AM Withdrawn 
F33.00003: An impurity in a heteronuclear twocomponent Bose mixture Giacomo Bighin We study the fate of an impurity in an ultracold heteronuclear Bose mixture, focusing on the experimentally relevant case of a 41K87Rb mixture, with the impurity in a 41K hyperfine state. Our work provides a comprehensive description of an impurity in a BEC mixture with contact interactions across its phase diagram. We present results for the miscible and immiscible regimes, as well as for the impurity in a selfbound quantum droplet. Here, varying the interactions, we find novel, exotic states where the impurity localizes either at the center or at the surface of the droplet. 
Tuesday, March 15, 2022 8:36AM  8:48AM 
F33.00004: Angular and radial densitydensity correlation function in a (2+1)dimensional sonic black hole in ultra cold BoseEinstein condensates and entanglement measure between the Hawking pairs : Inderpreet Kaur and Sankalpa Ghosh Sankalpa Ghosh, Inderpreet Kaur A quasi twodimensional sonic blackhole scenario where an ultra cold atomic BoseEinstein condensate (BEC) flows through an annular ringshaped supersonicsubsonic interface is considered [1]. We verify the existence of entanglement between the analogue Hawking pairs that emerges from the quantum character of the spontaneous Hawking radiation emitted from such configurations [2].We considered number of quasitwo dimensional cases that include spinorbit coupled (SOC) BEC [1] as well as quasi twodimensional BEC without any internal degrees of freedom and compare our results with the typical quasi onedimensional sonic black hole configurations.We studied in detail the radial and angular densitydensity correlations in such quasi two diemsnional systems. We also assess the participation of the phonon and the nonphononic part of the collective excitation spectrum [3] in the entanglement measure. 
Tuesday, March 15, 2022 8:48AM  9:00AM 
F33.00005: Fully fluctuating simulation of quantized vortices in rotating Bose Einstein Condensates at finite temperature Kimberlee Keithley, Glenn H Fredrickson, Kris T Delaney We investigate structures of quantized vortices in samples of rotating BoseEinstein condensates (BECs) of interacting particles at finite temperature in three dimensions using approximationfree fieldtheoretic simulations conducted with complex Langevin sampling. Most previous studies of such systems have been limited to mean field and zerotemperature analysis. Exact particlebased simulations at finite temperature, such as path integral Monte Carlo, are limited in the study of such systems due to the complex nature of the action. We present vortex structures in fully fluctuating simulations at finite temperature and investigate their relative stability as a function of temperature and rotational velocity. We also compare our results to those obtained with the static GrossPitaevskii equation, a mean field approximation that is often used in numerical studies of rotating dilute BECs. 
Tuesday, March 15, 2022 9:00AM  9:12AM 
F33.00006: Symmetryprotected BoseEinstein condensation of interacting hardcore Bosons Sebastian Paeckel, Thomas Köhler, Felix Alexander A Palm, Reja H Wilke The past two decades have seen the raise of practical applications of exotic quantum manybody phases. Proving their potential to overcome classical solution strategies to relevant problem settings, one of the main obstacles nowadays is to stabilize these highly fragile quantum states against perturbations. Here, we demonstrate the stabilization of a onedimensional quantum manybody phase, characterized by a certain wave vector k, from a kmodulated coupling to a center site via the protection of an emergent Z_{2 }symmetry. We illustrate this mechanism by constructing the solution to the full quantum manybody problem of hardcore bosons on a wheel geometry, which is known to form a BEC. The crucial step is to map the wheel to a projected ladder geometry, where the protection of the Z_{2} symmetry is manifested by the choice of a particular k mode spanning the projected subspace on one leg of the ladder. The robustness of the BEC is shown numerically by adding local interactions to the wheel Hamiltonian and we identify the energy scale that controls the protection of the emergent Z_{2} symmetry. Since the protection is generated by gapping out an independently selectable k mode from the singleparticle spectrum, our findings can be generalized, for instance to create a k≠0 BEC. 
Tuesday, March 15, 2022 9:12AM  9:48AM 
F33.00007: Topological and fracton order in Rydberg atom arrays Invited Speaker: Ruben Verresen Theoretical studies over the past decades have unearthed a rich picture of stronglyinteracting quantum states of matter with exotic order. These highlyentangled states are interesting, both at a conceptual level, as well as a tool for quantum metrology or quantum computation purposes. However, their experimental realization and detection has proven to be challenging. In this talk, I will review some of our proposals for realizing these states in Rydberg atom tweezer arrays. The ability to control individual atomsstronglyinteracting over a wide distancemake these arrays an ideal platform for realizing exotic manybody quantum states, whose nonlocal order parameters can be probed by imaging the whole array. We will explore the whole spectrum of short and longrange entanglement: from symmetryprotected topological phases, over cat states, to intrinsic topological order and even 3D fracton states. 
Tuesday, March 15, 2022 9:48AM  10:00AM 
F33.00008: Asymmetric Tunneling of BoseEinstein Condensates Dustin R Lindberg, Naceur Gaaloul, Jason Williams, Dennis Schlippert, Patrick B Boegel, Ernst M Rasel, Denys I Bondar In his celebrated textbook, Quantum MechanicsNonrelativistic Theory, Landau argued that, for single particle systems in 1D, tunneling probability remains the same for a particle incident from the left or the right of a barrier regardless of the shape of that potential barrier. We present a proof of this argument, as no rigorous proof currently exists. We then computationally show breaking of the leftright tunneling symmetry for BoseEinstein condensates (BEC) in 1D, modeled by the GrossPitaevskii equation. By varying the parameter, g, of interparticle interaction in the BEC, we demonstrate the transition from symmetric (g=0) to asymmetric tunneling is a threshold phenomenon. Our computations employ experimentally feasible parameters such that these results may be experimentally demonstrated in the near future. We conclude by suggesting applications of the phenomena to design atomtronic diodes, synthetic gauge fields, and blackhole analogues. 
Tuesday, March 15, 2022 10:00AM  10:12AM 
F33.00009: ThreeDimensional Numerical Simulations of BEC Transport Using Shortcuts to Adiabaticity Christopher J Larson We report on our numerical simulations of highfidelity, fast quantum control of BoseEinstein condensates (BECs) as we extend them to full 3D solutions of the GrossPitaevskii equation. We simulate a 3D painted potential that provides complete confinement of the atoms. Painted potentials allow for arbitrary and dynamic traps, which control the spatial transport of the BEC. To achieve high quantum fidelity after transport, we implement shortcutstoadiabaticity (STAs) to design the BEC trajectory in our simulations. STAs allow fast movement while suppressing excitations that can result due to the rapid transitions of the quantum state. In our 3D simulations, quantum fidelities resulting from different, experimentally viable transport times and trap depths are compared. Using the measured frequencies of the different traps and by simulating transport over multiples of those periods, we seek to identify and analyze a possible cause of lower than expected posttransport fidelities. 
Tuesday, March 15, 2022 10:12AM  10:24AM 
F33.00010: The kaleidoscope of phases in onedimensional Rydberg dressed Fermi gases Junhyun Lee, Pavel A Volkov, Brian DeSalvo, Jedediah H Pixley We theoretically investigate the ground state phases of a Rydbergdressed Fermi gas in a onedimensional optical lattice. The asymptotic low energy behavior of the system is calculated with bosonization (for weak interactions) and a strong coupling expansion (for strong Rydberg dressing), and both are verified with density matrix renormalization group calculations. The dressed Rydberg system has an attractive backscattering interaction for a certain momentum range, which can be directly controlled by tuning the filling. This results in quasilong range ordered phases alternating as a function of fermion density, when the interaction is weak. In contrast, the strong interactions are governed by the commensurate chargedensity wave states, similar to the PXPmodel in Rydberg systems. We present the phase diagram interpolating both limits, and discuss the experimental implications. 
Tuesday, March 15, 2022 10:24AM  10:36AM 
F33.00011: Domain wall dynamics in BoseEinstein condensates with densitydependent gauge field KaiXuan Yao, Zhendong Zhang, Cheng Chin We investigate the formation and dynamics of domain walls in a BoseEinstein condensate under a densitydependent gauge field. The densitydependent gauge field is created by simultaneous modulations of an optical lattice potential and interatomic interactions, and results in domains of atoms condensed into two different momenta. We observe deterministic formation of domain walls due to the density inhomogeneity of the atomic cloud. We further study the dynamics of the domain walls under a synthetic electric field. Modeling the topological defects as elementary excitations, we find that they respond to the electric field with an effective chargetomass ratio larger than and opposite to that of the bare atoms. 
Tuesday, March 15, 2022 10:36AM  10:48AM 
F33.00012: Finite momentum condensate with pwave interaction Mingyang Liu, Shizhong Zhang A system of “spin½” bosons with pwave interaction can be a promising candidate for realizing a fragmented BoseEinstein condensate known as the KSA state. In this talk, I show that the KSA state has lower energy than the standard condensate states that is explored so far in literature. Furthermore, I investigate the elementary excitations of the KSA state. Importance of the role of effective range will be emphasized in the talk. 
Tuesday, March 15, 2022 10:48AM  11:00AM 
F33.00013: Deep Learning framework towards automated experiments and quantum simulations Ayana Ghosh, Bobby G Sumpter, Ondrej Dyck, Sergei V Kalinin, Maxim Ziatdinov Datasets with natural images where availability of thousands of samples with large variabilities are present, common deep learning (DL) classification strategies work well. However, for datasets consisting atomically resolved images, networks are required to rapidly adapt to changes to imaging conditions and successfully locate features (nearly identical objects) to make the analyses efficient. The differences in experimental and simulation parameters lead to outofdistribution drifts. This work introduces DL workflow of ensemble learning and iterative training (ELIT) as an alternative strategy to surpass such challenges. The EL allows for selection of artifactfree features and pixelwise uncertainty maps by combining multiple networks. The IT part retrains the networks with already realized features, focusing its attention on features present in the data. The features are then used to construct simulation objects to perform firstprinciples simulations for geometry optimization, property evaluation and temperaturedependent dynamics. Overall, these workflows may be used to better guide experiments while learning from theoretical models. 
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