Bulletin of the American Physical Society
54th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 68, Number 7
Monday–Friday, June 5–9, 2023; Spokane, Washington
Session H06: Dynamics in Trapped Gases |
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Chair: David Weld, UC Santa Barbara Room: 206 A |
Wednesday, June 7, 2023 8:00AM - 8:12AM |
H06.00001: The anomalous Floquet Anderson insulator as a Laughlin charge pump Arijit Dutta, Jun-Hui Zheng, Monika Aidelsburger, Walter Hofstetter Periodically driven systems can host analogues of equilibrium topological phases, like the Haldane phase, which obey the usual bulk-boundary correspondence. However, due to the periodic nature of the quasienergy spectrum, these systems can host anomalous topological phases where the bulk properties do not characterize the behaviour at the edges. Further, adding disorder can lead to complete localization of the bulk states while supporting topological charge pumping - a signature of the anomalous Floquet Anderson insulator (AFAI) phase. Working with the experimentally realized model reported in Wintersperger et. al. Nat. Phys. 16, 1058–1063 (2020), we establish the presence of the AFAI phase and study its transition to the Anderson insulating phase. We calculate charge pumping in a Laughlin charge pump setup and discuss issues relevant for experimental realization. |
Wednesday, June 7, 2023 8:12AM - 8:24AM Withdrawn |
H06.00002: Enumerating cat scars analytically in clean discrete time crystals Biao Huang We construct an analytical theory to enumerate and characterize the scar eigenstates responsible for non-prethermal clean discrete time crystal (DTC) dynamics. The results include two parts. First, we introduce a projective symmetry indicator method to quickly identify all possible scars leading to clean DTC phenomena. Importantly, the symmetry indicator predicts the coexistence of ferromagnetic and antiferromagnetic scars, with the latter unnoticed before in clean systems. The inhomogeneous anti-ferromagnetic DTC patterns offer a valuable opportunity to distinguish local clean DTC oscillations from certain short-lived homogeneous global oscillations based on early-time data accessible to experiments. Second, we prove three analytical scaling relations characterizing the DTC amplitudes, Fock space localization, and lifetime, where the bounds for scaling exponents are analytically given by simply counting how many operators are multiplied in perturbation Hamiltonians. These two results pave the way to a systematic understanding and classification of clean DTCs based on spatial symmetries, and also to future connections of clean and disordered DTCs in a unified scheme. |
Wednesday, June 7, 2023 8:24AM - 8:36AM |
H06.00003: Observation of channel turbulence accompanying a rarefaction flow of a Bose-Einstein condensate Maren E Mossman, Judith Gonzalez Sorribes, Mark A Hoefer, Peter W Engels Understanding turbulence is one of the great challenges in modern hydrodynamics research. In a superfluid, the emergence of solitons and quantized vorticity in regions of turbulence leads to particularly interesting dynamics, yielding an effective viscosity in a nominally dissipationless fluid. In our previous work, we have employed a quantum mechanical piston geometry to generate a region of turbulence in a trapped Bose-Einstein condensate, and have showcased the interplay of vortices and shocks leading to an effective viscosity in the system. Here, we expand on this work and demonstrate the emergence of channel turbulence from a considerably simpler geometry: expansion into a wet-channel accompanied by rarefaction waves. This geometry provides a method for the highly repeatable and controllable generation of turbulence, allowing us to conduct detailed studies of system parameters determining the onset of turbulence. Our experimental results are corroborated by matching numerical studies. This approach to generate channel turbulence in a superflow provides important benchmark data for theoretical modeling, and opens new avenues for research, such as the merging of two turbulent regions which we also demonstrate in prototypical experiments. |
Wednesday, June 7, 2023 8:36AM - 8:48AM |
H06.00004: Dense soliton complexes in a two-component Bose-Einstein condensate Sean Mossman, Garyfallia Katsimiga, Simeon I Mistakidis, Alejandro Romero-Ros, Thomas M Bersano, Peter Schmelcher, Panayotis Kevrekidis, Peter W Engels Many natural phenomena are understood at a fundamental level but exhibit complex dynamics which require statistical methods of analysis in practice. The dynamics of nonlinear waves in integrable systems has arisen as a potentially revelatory framework for understanding the emergence of complexity in this context. Of interest here, collections of localized nonlinear waves known as solitons, while being mathematically understood individually, can exhibit sufficiently random dynamics to be better described as a kind of soliton gas. |
Wednesday, June 7, 2023 8:48AM - 9:00AM |
H06.00005: Observation of the Interacting 3D Anderson Metal Insulator Transition with Kicked Quantum Gases Xinxin Tang, Jun Hui See Toh, Nicolas Williams, Carson Patterson, Mengxin Du, Ying Su, Chuanwei Zhang, Subhadeep Gupta Quantum transport in disordered systems is a long-standing fundamental problem that continues to pose challenges, especially in the presence of many-body interactions. |
Wednesday, June 7, 2023 9:00AM - 9:12AM |
H06.00006: Complex Langevin methods for approximation-free simulation of cyclically driven quantum gasses Kimberlee Keithley, Ethan Q Simmons, Roshan Sajjad, Hector Mas, Jeremy Tanlimco, Eber Nolasco-Martinez, Kris T Delaney, Glenn H Fredrickson, David M Weld We numerically simulate an interaction-driven thermodynamic cycle with a Bose-Einstein condensate of 7Li as the working fluid in full 1:1 scale and at finite temperature. We use the coherent states field theoretic formulation of the path integral rather than a particle coordinate-based formulation to simulate large, high density systems at finite temperature without simplifying approximations, allowing for in-principle exact calculation of release energy, total energy, and entropy. Complex Langevin sampling enables efficient evaluation of the partition function without a sign problem. This combination allows us to exactly replicate the size, temperature, and density of an experimental realization of a four stroke cycle with over 200,000 atoms that alternates strokes of trap compression/expansion with strokes of scattering length increase/decrease. We demonstrate the accuracy and viability of these methods via direct comparison with experimental measurements. |
Wednesday, June 7, 2023 9:12AM - 9:24AM |
H06.00007: Degenerate 39K Bose gases in dynamic size-tuneable box traps Konstantinos Konstantinou, Paul Wong, Tanish Satoor, Chris Eigen, Zoran Hadzibabic, Nishant Dogra Homogeneous atomic clouds in optical box potentials have allowed novel experiments on phenomena such as the second sound, critical dynamics and turbulence, which are much harder, or in some cases impossible, to study in the more common harmonic traps, where the atomic density is inhomogeneous [1]. However, the production of box-trapped atomic gases has so far relied on an intermediate cooling step in harmonic traps. Extending the capabilities of box traps, we use electrically controlled focus-tuneable lenses to create optical boxes (for 39K atoms) whose size can be changed in real time. This allows for direct transfer of laser-cooled clouds into a box trap and runaway evaporation via independent control of the trap depth and the collision rate; moreover the initial conditions for evaporation can be improved by performing laser cooling on clouds already trapped in the dark box [2]. Beyond improving the production of homogeneous gases, the dynamically tuneable boxes open further possibilities for many-body experiments with degenerate gases, including studies of thermodynamics in dynamical containers and the attainment of high-density homogeneous gases that are favourable for experiments on collective light scattering [3]. We will give an overview of our first experiments with these novel traps. |
Wednesday, June 7, 2023 9:24AM - 9:36AM |
H06.00008: Observation of anisotropic superfluid density in an artificial crystal Junheng Tao, Mingshu Zhao, Ian B Spielman We experimentally and theoretically investigate the anisotropic speed of sound of an atomic superfluid (SF) Bose-Einstein condensate in a 1D optical lattice. Because the speed of sound derives from the SF density, this implies that the SF density is itself anisotropic. We find that the speed of sound is decreased by the optical lattice, and the SF density is concomitantly reduced. This reduction is accompanied by the appearance of a normal fluid in the purely Bose condensed phase. The reduction in SF density---first predicted [A. J. Leggett, Phys. Rev. Lett. 1543--1546 (1970)] in the context of supersolidity---results from the coexistence of superfluidity and density modulations, but is agnostic about the origin of the modulations. We additionally measure the moment of inertia of the system in a scissors mode experiment, demonstrating the existence of rotational flow. |
Wednesday, June 7, 2023 9:36AM - 9:48AM |
H06.00009: Controlled expansion of shell-shaped Bose-Einstein condensates Patrick B Boegel, Alexander Wolf, Matthias Meister, Maxim Efremov Motivated by the recent experimental realization of ultracold quantum gases in shell topology [1], we propose a straightforward implementation of matter-wave lensing techniques for shellshaped Bose-Einstein condensates [2]. This approach allows to significantly extend the free evolution time of the condensate shell after release from the trap and enables the study of novel quantum many-body effects on curved geometries. With both analytical and numerical methods, we derive optimal parameters for realistic schemes to conserve the shell shape of the condensate for times up to hundreds of milliseconds. |
Wednesday, June 7, 2023 9:48AM - 10:00AM |
H06.00010: Exploring Modeling Techniques in BEC Atom-Interferometry Ryan Corbin, Michael M Forbes, Maren E Mossman, Peter W Engels We find semiclassical (WKB) techniques to be effective for analyzing atom interferometry in Bose-Einstein Condensates. These allow inexpensive simulations to reproduce fine details of matter-wave interference seen in multi-component BEC atom-laser experiments. In this talk I will discuss how to use phase-retrieval techniques for tomographic reconstruction of the underlying potentials from the observed interference patterns. The reconstructed potentials are used to confirm the validity of the simplified WKB approximation, laying the foundation for a new quantum imaging technique based on matter-wave interferometry. |
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