Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session E28: Strongly Interacting Quantum Gases IILive
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Sponsoring Units: DAMOP Chair: Ariel Sommer, Lehigh Univ |
Tuesday, March 16, 2021 8:00AM - 8:12AM Live |
E28.00001: Approximation-free simulation of finite temperature field theory for interacting bosons in a rotating trap Kimberlee Keithley, Kris T Delaney, Glenn H Fredrickson We investigate rotating dilute Bose-Einstein condensates (BECs) of interacting particles at finite temperature using approximation-free field theoretic methods. Exact particle-based 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. A previous work detailed a numerical scheme that allowed efficient and accurate sampling of the coherent states field theory form of the bosonic path integral, and demonstrated its viability by locating the critical phase transition in an interacting Bose gas. In the present work, we apply the same algorithms to a more complex problem of rotating BECs in a harmonic trap that so far has been limited to mean-field and zero temperature analysis. We first validate our method by comparison with mean-field studies, and present new results from fully-fluctuating simulations at finite temperature. |
Tuesday, March 16, 2021 8:12AM - 8:24AM Live |
E28.00002: Cavity quantum-electrodynamics with pairs in a strongly interacting Fermi gas Kevin Roux The last decade has seen a convergence of concepts and methods between many-body physics and quantum optics, exemplified by the use of quantum gases as simulators for many-body phenomena. Cavity QED has however been restricted to a thermal or Bosonic atoms, without the ability to control independently the atom-atom and light matter interactions.I will present the experimental realization of a quantum-degenerate, strongly interacting Fermi gas coupled to a high-finesse cavity. |
Tuesday, March 16, 2021 8:24AM - 8:36AM Live |
E28.00003: KSS viscosity bound violation in holographic duals to ultra-massive hairy black holes Luke Martin, Joshuah Heath, Kevin Shawn Bedell Using the AdS/CFT correspondence, it has been shown that the ratio of shear viscosity to entropy density is bounded from below in strongly coupled field theories with a gravity dual. More recently, this bound has been shown to be grossly violated in novel non-Fermi liquids and the unitary Fermi gas in the presence of superfluid fluctuations above Tc. Nevertheless, a holographic approach to such systems which break the lower bound have been strongly reliant on AdS spacetimes with massive gravitons. In this work, we propose a violation of the viscosity over entropy bound in 3+1D AdS spacetimes that support stable black hole solutions with non-zero scalar field. Such a black hole is shown to be characterized by a novel phase transition at large negative mass, where the underlying thermodynamics agrees with the Larkin-Ovchinnikov-Fulde-Ferrell (LOFF)-like phase seen in the unitary Fermi gas near Tc and the bound is similarly broken. Such a work paves the way for a holographic description of strongly-entangled quantum fluids at high Reynolds number. |
Tuesday, March 16, 2021 8:36AM - 8:48AM Live |
E28.00004: Theory of Anti-Hund's Rule in Two-species Bosons in the p-orbital Bands Jhih-Shih You, I-Kang Liu, Congjun Wu We study a model of interacting two-species bosons that occupy the first excited p-band states of a |
Tuesday, March 16, 2021 8:48AM - 9:00AM Live |
E28.00005: Thermodynamics in shell-shaped Bose-Einstein condensates Brendan Rhyno, Courtney Lannert, Nathan Lundblad, David Aveline, Smitha Vishveshwara Inspired by investigations of Bose-Einstein condensates (BECs) produced in the Cold Atom Laboratory (CAL) aboard the International Space Station (ISS), we present a study of thermodynamic properties of shell-shaped BECs. Within the context of a 'bubble-trap potential', we compute the BEC critical temperature and the evolving temperature of the gas during an adiabatic expansion process that leads to the hollowing of a spherically symmetric ultracold atomic gas. We employ multiple theoretical approaches and find that the standard semiclassical approximation breaks down in the quasi-2D limit. We investigate the topological filled-to-hollow sphere transition and the ensuing crossover from 3D to 2D physics. We address the relevance of interactions in shell-shaped geometries and the thermodynamics of the resulting collective excitations. We compare our results with the experimentally realistic situation and identify the parameter regimes and phenomena directly relevant to the CAL setting. |
Tuesday, March 16, 2021 9:00AM - 9:12AM Live |
E28.00006: Universality in one-dimensional scattering with general dispersion relations Yidan Wang, Michael J. Gullans, Xuesen Na, Alexey V Gorshkov Many synthetic quantum systems allow particles to have dispersion relations that are neither linear nor quadratic functions. Here, we explore single-particle scattering in one dimension when the dispersion relation is any analytic function. We show that, when the density of states diverges at energy E0, the S-matrix evaluated at an energy E->E0 converges to a universal limit that is only dependent on the rate of divergence of the density of states at E0. This behavior is independent of the nature of the interactions, a feature that we illustrate by considering two distinct scattering problems: a single-particle in a one dimensional waveguide (i) scattering off of a localized potential(“potential” scattering) and (ii) scattering off of an inhomogeneous, discrete set of sites locally coupled to the waveguide (“impurity” scattering). We also give a generalization of a key result in quantum scattering theory known as Levinson’s theorem—which relates the scattering phases to the number of bound states—to these more general dispersion relations |
Tuesday, March 16, 2021 9:12AM - 9:24AM Live |
E28.00007: Universal intrinsic higher-rank spin Hall effect Junpeng Hou, Chuanwei Zhang Spin Hall effect (SHE), a fundamental transport phenomenon with non-zero spin current but vanishing charge current, has important applications in spintronics for the electrical control of spins. Owing to the half-spin nature of electrons, the rank of spin current (determined by the rank of the spin tensor) has been restricted to 0 and 1 for charge and spin Hall effects. Motivated by recent studies of pseudospin-1 fermions in solid-state and cold atomic systems, here we introduce and characterize higher-rank SHEs in large spin systems. We find a universal rank-2 spin Hall conductivity (with zero rank-0 and 1 conductivities) for a spin-1 model with intrinsic spin-orbit (SO) coupling. Similar rank-2 SHEs can also be found in a spin-3/2 system. An experimental scheme is proposed to realize the required SO coupling for rank-2 SHEs with pseudospin-1 fermionic atoms in an optical lattice. Our results reveal novel spin transport phenomena in large spin systems and may find important applications in designing innovative spintronic devices. |
Tuesday, March 16, 2021 9:24AM - 9:36AM Live |
E28.00008: Effect of interactions in the interference pattern of Bose-Einstein condensates Alessia Burchianti, Chiara D'Errico, Lorenzo Marconi, Francesco Minardi, Chiara Fort, Michele Modugno Understanding the effect of interactions in the phase evolution of expanding atomic Bose-Einstein condensates is fundamental to describing the basic phenomenon of matter wave interference. Many theoretical and experi- mental works tackled this problem, always with the implicit assumption that the mutual interaction between two expanding condensates rigidly modifies the phase evolution through an effective force. In this paper, we present a combined experimental and theoretical investigation of the interference profile of expanding 87Rb condensates, with a specific focus on the effect of interactions. We come to the different conclusion that the mutual interaction produces local modifications of the condensate phase only in the region where the wave packets overlap. |
Tuesday, March 16, 2021 9:36AM - 9:48AM Live |
E28.00009: Exciton states in a frozen Rydberg gas Ghassan Abumwis, Matthew Eiles, Alexander Eisfeld The long-range dipole-dipole interaction between excited Rydberg |
Tuesday, March 16, 2021 9:48AM - 10:00AM Live |
E28.00010: Momentum-space entanglement as a probe of interactions Long Hin Tang, Christopher Laumann, Anushya Chandran Momentum-space entanglement quantifies the effects of interactions, orbital mixing and fermion-pairing in fermionic systems. The associated entropy is experimentally accessible through time-of-flight measurements in quantum optical systems. We discuss the behavior of the entropy near gapless Dirac points, in p-wave superconductors, and in Fermi liquids. |
Tuesday, March 16, 2021 10:00AM - 10:12AM Live |
E28.00011: Revealing the Hidden Bosonic Many-Body Nature of the Jaynes-Cummings Interaction Aniruddha Bhattacharya, Kevin Smith, David J Masiello The Jaynes-Cummings Hamiltonian (JCH) is one of the simplest and most versatile models in quantum optics. The similarity of the JCH with the nonlinear Kerr Hamiltonain having two-body bosonic interaction terms has been previously explored in the literature. However, the many-body character has either been postulated or deduced by matching coefficients to obtain the correct eigenvalue spectrum, especially in the limit of a few quanta. In the present work, we have theoretically examined, in a systematic fashion, the many-body nature of the JCH. A procedure for obtaining the coefficients of the normally ordered many-body terms, describing the interactions between the bosonic dressed states, has been devised. We show how such terms originate in the case of a linear cavity coupled to a two-level system, in the absence of Kerr-like non-linear optical susceptibilities. The coefficients are independent of the number of quanta stored in the system similar to the Bose-Hubbard models in atomic physics. We have verified that the many-body version of the JCH has identical eigenvalues, eigenvectors and steady-state transmission response as the usual representation. Our work should better guide experiments on quantum simulation of few-body effects. |
Tuesday, March 16, 2021 10:12AM - 10:24AM Live |
E28.00012: Decay routes of Monopole Textures in spin-1 and spin-2 condensates. Roberto Zamora-Zamora, Alina A Blinova, Tuomas Ollikainen, David Sumner hall, Mikko Möttönen The dynamical evolution of spin-1 and spin-2 Bose-Einstein condensates provides a novel way to understand topological phenomena in macroscopic quantum systems. We determine dynamical decaying routes of imprinted monopole defects within the polar phase (spin-1) and uniaxial nematic phase (spin-2). By numerically solving Gross-Pitaevskii equations under experimental conditions, we find that the monopole decay into a robust |
Tuesday, March 16, 2021 10:24AM - 10:36AM Live |
E28.00013: Chiral Edge Modes in Helmholtz-Onsager Vortex Systems Vishal Patil, Jorn Dunkel Vortices play a fundamental role in the physics of 2 dimensional (2d) fluids across a range of length scales, from quantum superfluids to geophysical flows. Despite a history dating back to Helmholtz, the study of point vortices in a classical 2d fluid continues to be of interest, owing to their unusual statistical mechanics. Recent experiments show that this model confirms the phenomenon of vortex condensation in superfluids. However, the effects of boundary geometry in the subcritical energy regime have not yet been explored in detail. Here we show that confined Helmholtz-Onsager systems contain edge modes at subcritical energy, extending a previously identified analogy between vortex matter and quantum Hall systems. Through numerical simulations and mean field models, we demonstrate that angular momentum conservation in a disk leads to a symmetry protected edge mode. These edge modes are robust, persisting in nonconvex domains. Furthermore, using analytics and numerical simulations, we exhibit a subcritical phase separation associated with edge modes in neutral Helmholtz-Onsager systems at finite particle number. |
Tuesday, March 16, 2021 10:36AM - 10:48AM Live |
E28.00014: Degenerate Fermi gases in a triangular optical lattice Jin Yang, Liyu Liu, Jirayu Mongkolkiattichai, Davis Garwood, Peter Schauss Geometric frustration is a path towards realizing spin liquids and exotic spin ordering. Ultracold atom systems offer great tunability to study such systems in a wide parameter range of interactions, density and spin-imbalance which are not accessible in condensed matter systems. |
Tuesday, March 16, 2021 10:48AM - 11:00AM Live |
E28.00015: Dynamical quantum phase transitions in a system of interacting bosons Sebastian Stumper, Michael Thoss, Junichi Okamoto One way to generalize the concept of quantum criticality to non-equilibrium situations is to define dynamical quantum phase transitions as zeros of the Loschmidt echo, which serves as a dynamical analog of the partition function [Rep. Prog. Phys. 81, 054001 (2018)]. Here, we study quench dynamics in the one-dimensional extended Bose-Hubbard model using the time-dependent variational principle with matrix product states. The model offers a rich phase diagram, including the gapped Mott insulator (MI), Haldane insulator (HI) and charge density wave (CDW) phases. After initializing the system in generic ground states corresponding to these phases and a sudden quench of the on-site and nearest-neighbor interactions, we analyze how the occurrence of dynamical quantum phase transitions relates to the equilibrium phase transitions. A particular emphasis is placed on the topological MI-HI and HI-CDW transitions, as well as the dynamics of various non-local string order parameters that characterize the ground states. |
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