Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session S65: Bose-Einstein Condensates II |
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Sponsoring Units: DAMOP Chair: Tsz-Chun Wu, Rice University Room: Room 414 |
Thursday, March 9, 2023 8:00AM - 8:12AM |
S65.00001: Localization and ergodicity breaking in long-range self-dual models with correlated disorder Shilpi Roy Self-dual Aubry-Andr'e model provides an example of a system with the fully correlated quasiperiodic disorder potential, which demonstrates the Anderson transition already in a one-dimensional system. Its self-dual cousin with uncorrelated disorder and all-to-all translation-invariant (TI) coupling, known as a TI Rosenzweig-Porter ensemble, carries along with the ergodic and localized phases also a fractal one. In this paper, we consider an interpolation between the above two models, characterized by both the power-law correlated diagonal elements and the TI off-diagonal elements, power-law decaying with a distance from the diagonal. We show that the interplay of the partially correlated disorder and the power-law decay hopping terms may lead to the emergence of the two types of the fractal phases in an entire range of parameters, even without having any quasiperiodicity of the Aubry-Andr'e potential. |
Thursday, March 9, 2023 8:12AM - 8:24AM |
S65.00002: ELEMENTARY DESCRIPTION OF BOSE EINSTEIN CONDENSATE. Pritam Dutta
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Thursday, March 9, 2023 8:24AM - 8:36AM |
S65.00003: Overcoming the sign problem in rotating Bose Einstein Condensates Kimberlee Keithley, Kris T Delaney, Glenn H Fredrickson We numerically investigate the structure and thermodynamic properties of quantized vortices in samples of rotating Bose-Einstein condensates of interacting particles at finite temperature in three dimensions. Thus far, numerical study of such systems has been largely limited to mean field and zero-temperature analysis. Exact particle-based simulations at finite temperature, such as path integral Monte Carlo, are limited in this regime due to the complex nature of the action. To circumvent this problem, we employ coherent states field theoretic methods rather than particle coordinate methods, and Complex Langevin sampling rather than Monte Carlo sampling. We visualize quantized vortices in fully fluctuating simulations at finite temperature, and calculate the free energy of a select number of energetically competitive arrangements of vortices as a function of rotation speed and temperature to create a vortex phase diagram. |
Thursday, March 9, 2023 8:36AM - 8:48AM |
S65.00004: Expansion dynamics of a shell-shaped Bose-Einstein condensate LiYuan Qiu, Fan Jia, Zerong Huang, Rongzi Zhou, Yangqian Yan, Dajun Wang Bose-Einstein condensates (BECs) confined on shell-shaped surfaces have been proposed as a platform for exploring many nontrivial quantum phenomena on curved spaces. However, as the shell-shaped trapping potential generated with the conventional radio frequency dressing method is very sensitive to gravity, so far experimental studies of shell BECs can only be performed in micro-gravity environments. Here, we overcome this difficulty and create a shell BEC in presence of Earth's gravity with immiscible double species BECs of sodium and rubidium atoms. After eliminating the displacement between the centers of mass of the two BECs with a magic wavelength optical dipole trap, the interspecies repulsive interaction ensures the formation of a closed shell of sodium atoms with its center filled by rubidium atoms. Releasing the double BEC together from the trap, we observe explosion of the shell accompanied by energy transfer from the inner BEC to the shell BEC. With the inner BEC removed, we obtain a hollow shell BEC which shows self-interference as a manifestation of implosion. At the same time, we can tune the interaction between the double BEC system and further explore the rich dynamics of the shell double BEC system. |
Thursday, March 9, 2023 8:48AM - 9:00AM |
S65.00005: Field Theoretic Simulations of a Finite Temperature Stripe Phase Found in Spin-orbit Coupled Bosons Ethan C McGarrigle, Kris T Delaney, Leon Balents, Glenn H Fredrickson We investigate the finite-temperature properties of interacting bosons endowed with an artificial spin-orbit coupling (SOC) in two dimensions. Using complex Langevin sampling of coherent states fields representing each hyperfine state, we access the equilibrium properties of spin-orbit coupled, pseudo-spin 1/2 bosons without approximation, despite the presence of a sign problem inherent to the SOC boson model. The Hamiltonian of interest admits two non-trivial BEC phases at the mean-field level — a stripe and plane-wave phase — due to the presence of degenerate single-particle ground states at non-zero momenta. This talk focuses on the stripe phase with smectic character and details the impact of thermal fluctuations on its characteristic pseudo-spin and momentum-space ordering. Furthermore, phase transitions are discussed in the context of weak crystallization Brazovskii theory as well as Berezinski-Kosterlitz-Thouless transitions characteristic of two-dimensional Bose gases. |
Thursday, March 9, 2023 9:00AM - 9:12AM |
S65.00006: Phases and dynamics of the one-dimensional interacting bosons with double-well dispersion role Jay D Sau, Yang-Zhi Chou Spin-orbit coupling as well as Floquet techniques can generate dispersion for one dimensional Bosons with a double well dispersion. This leads to a Z2 symmetry breaking Lifshitz quantum critical point and allows for a rich phase diagram for the interacting bosons, distinctive from the well-established Lieb-Liniger model. Using a combination of effective models as well as mapping to fermions, we construct a phase diagram and study the effect of quantum fluctuations generated by strong interactions on the phases as well as dynamical response in the vicinity of the quantum critical point. Specifically, we will discuss a phase with more than one gapless mode as well as an unusual domain wall dynamics in the Z2 symmetry broken phase. |
Thursday, March 9, 2023 9:12AM - 9:24AM |
S65.00007: Optical-plug-assisted spin vortex in a 87Rb dipolar spinor Bose-Einstein condensate Hui Tang Generating a spin vortex in a 87Rb dipolar spinor Bose-Einstein condensate in a controllable way is still experimentally challenging. We propose an experimentally easy and tunable way to produce spin vortex by varying the potential barrier height and the width of an additionally applied optical plug. A topological phase transition occurs from the trivial single mode approximation phase to the optical-plug-assisted-vortex one, as the barrier height increases and the width lies in an appropriate range. The optical plug causes radial density variation thus the spin vortex is favored by significantly lowering the intrinsic magnetic dipolar energy. A type of coreless spin vortex, different from the conventional polar core vortex, is predicted by our numerical results. Our proposal removes a major obstacle to investigate the topological phase transition in a 87Rb dipolar spinor BEC. |
Thursday, March 9, 2023 9:24AM - 9:36AM |
S65.00008: Topological behavior of a neutrals spin-1/2 particle in a background magnetic field Bernard Zygelman Following a suggestion in [J. March-Russell, J. Preskill, and F. Wilczek, Phys. Rev. Lett. 68, 2567 (1992)] we present results of a numerical experiment in which a neutral spin-1/2 particle is subjected to a static magnetic vortex field as passes through a double slit barrier. We demonstrate that the resulting interference pattern on a detection screen exhibits fringes that are identical to that produced by a charged particle undergoing Aharonov-Bohm (AB) scattering. We provide analytic solutions to systems that exhbit synthetic gauge fields that allow an SU(2) generalization of AB scattering. We provide an expression for the partition function in which the dependence of the Wilson loop integral of the synthetic gauge potential is explicit and demonstrates a topological phase transition. We explore the interference between fundamental gauge fields (i.e. electromagnetism) with effective synthetic gauge potentials. We propose a possible laboratory demonstration for the latter in an ion trap setting. We illustrate how effective gauge potentials influence wave-packet revivals in the said ion trap. |
Thursday, March 9, 2023 9:36AM - 9:48AM |
S65.00009: Berezinskii-Kosterlitz-Thouless transition in a binary Bose mixture with Rabi coupling Koichiro Furutani, Andrea Perali, Luca Salasnich We discuss the Berezinskii-Kosterlitz-Thouless transition in a 2D binary Bose mixture with Rabi coupling under balanced densities. Adopting the Nelson-Kosterlitz renormalization group approach, we clarify the dependence of the Berezinskii-Kosterlitz-Thouless transition temperature on the Rabi coupling and the inter-component coupling. In particular, we find an amplification of the transition temperature with respect to the one in the single-component case for finite values of Rabi coupling and small intra-component couplings. We also evaluate the first sound and second sound velocity, which exhibits suppression of quasicrossing of the two sound modes with a finite Rabi coupling in the low-temperature regime. |
Thursday, March 9, 2023 9:48AM - 10:00AM |
S65.00010: Spinor boson droplets stabilized by spin fluctuations Mehmet O Oktel, Ahmet Keles, Taha Alper Yogurt Self-trapped droplets stabilized by quantum fluctuations have been experimentally realized in dipolar gases and binary boson mixtures. We investigate spinor Bose gases as another candidate for droplet formation. For spin-1 gas, we find that spin fluctuations give a dilute but self-trapped state for two different order parameters where the mean-field picture predicts collapse. A polar droplet phase can be stabilized by spin fluctuations for antiferromagnetic and ferromagnetic spin-dependent coupling. An antiferromagnetic droplet phase can be stabilized similarly with a negative quadratic Zeeman shift. The beyond mean-field energy of the system depends on the quadratic Zeeman coupling, which provides a mechanism to tune the droplet formation and its density. Similarly, the total magnetic polarization of the system provides another tunable parameter for controlling the droplets. We calculate the phase diagram of the system as a function of polarization and quadratic Zeeman shift. |
Thursday, March 9, 2023 10:00AM - 10:12AM |
S65.00011: Properties of Dipolar Impurities in a Dipolar Medium Neelam Shukla, Artem G Volosniev, Jeremy R Armstrong Some of the most challenging problems in many-body physics are due to relaxation dynamics in closed quantum systems. The understanding of these dynamics is not only important in quantum statistical physics but also an open problem in diverse fields including high-energy physics, quantum information, and cosmology [1]. An ideal model to answer those problems is an impurity interacting with a quantum environment. In this work, we study a dipolar polaron, an impurity in a Bose gas of trapped dipoles in an isotropic harmonic trap. The dipolar polaron would be a dipole with at least one different property than the medium, such as a different hyperfine state, mass, or dipole moment. An external field aligns the dipole moments along the z-axis. Since the dipole-dipole interaction is both anisotropic and long-range, the dipole-polaron system would have both attractive and repulsive interactions depending on direction. Thus, we have studied and calculated the various properties of this impurity in two-dimensional (2D) and three-dimensional (3D) spaces. For this purpose, we solved the modified Gross-Pitaevskii (GP) equation by employing the split-step Crank-Nicolson method]. In 2D, the calculation has been carried out for two geometries: when the plane is perpendicular and when the plane is parallel to the polarization direction. The properties like self-energy and density of the impurity are calculated in the thermodynamic limit for different numbers of particles and impurity strengths for the stationary states. In addition, these results are calculated for different angles, i.e., the angle between the system’s dipoles and the dipolar polaron impurity. Further, by introducing another impurity into the system, we calculated the impurity-impurity interaction energy as a function of impurity strengths. Thereafter, in 3D, we solved the GP equation involving time dynamics with one impurity. We observed from the results that after introducing the impurity into the system it is showing anisotropic response in quench dynamics. |
Thursday, March 9, 2023 10:12AM - 10:24AM |
S65.00012: Study of strongly interacting spinor gases in an optical lattice using a generalized effective spin chain Hamiltonian Sagarika Basak, Han Pu We study one-dimensional strongly interacting spinor gases in an optical lattice by mapping it to an effective spin chain Hamiltonian. Previous work (Phys.Rev.A 91, 043634, 2015; Phys.Rev.A 95, 043630, 2017) demonstrated a mapping of a continuum one-dimensional spinor gas with contact s-wave interaction to the direct product of the wave function of a spinless Fermi gas with short-range p-wave interaction and a spin system governed by spin-parity projection operators. The mapping allowed for a generalized spin-chain model that captures the static and dynamics properties of the system. Here, this is extended to lattice systems, thereby providing a computationally efficient tool to study strongly interacting spinor gases in an optical lattice as an alternative to t–J Model and slave particle formalism. It allows us to study gases with arbitrary spin and statistics, providing a universal approach for one-dimensional strongly interacting gases. The spin-chain formalism by virtue of its simple definition, provides an easier analysis tool compared to the t–J model and slave particle formalism. Additionally, the extension provides an approach to study them in-continuum or in-lattice, and can be easily extended to SU(n) gases, demonstrating the wide applicability of the spin-chain model. The mapped system reproduces the ground states of the t–J model, momentum distributions and spin correlations studied for Fermi-Hubbard Hamiltonian (Phys.Rev.B 41, 2326, 1990), and the dynamics of 1D lattice gases for large on-site interaction. The spin-chain Hamiltonian is useful in the study of a multitude of interesting phenomena arising in lattice systems such as high-Tc superconductivity, the spin-coherent Luttinger liquid and the spin-incoherent Luttinger liquid regimes. |
Thursday, March 9, 2023 10:24AM - 10:36AM |
S65.00013: Cooling and heating in the Bose-Hubbard model by parameter tuning Sebastian Eggert, Sven Stawinski, Axel Pelster We investigate short-range interacting Bosons in an optical lattice at finite temperature. It is well known that the system shows a Mott-Superfluid transition when changing the repulsion U, the hopping t and/or the filling. However, it is much less clear how the temperature is affected by those changes, assuming the parameters U and/or t are tuned adiabatically. We now present higher order calculations for the full Free energy and derive the temperature and entropy in a large parameter space. We discuss where significant heating or cooling effects can be expected in the superfluid phase, in the Mott region and near the phase transition lines. |
Thursday, March 9, 2023 10:36AM - 10:48AM |
S65.00014: Fractonic Luttinger Liquids and Supersolids in a Constrained Bose-Hubbard Model Johannes Feldmeier, Philip Zechmann, Ehud Altman, Michael Knap Quantum many-body systems with fracton constraints are widely conjectured to exhibit unconventional low-energy phases of matter. In this work, we demonstrate the existence of a variety of such exotic quantum phases in the ground states of a dipole-moment conserving Bose-Hubbard model in one dimension. For integer boson fillings, we perform a mapping of the system to a model of microscopic local dipoles, which are composites of fractons. We apply a combination of low-energy field theory and large-scale tensor network simulations to demonstrate the emergence of a novel dipole Luttinger liquid phase. At non-integer fillings our numerical approach shows an intriguing compressible state described by a quantum Lifshitz model in which charge density-wave order coexists with dipole long-range order and superfluidity -- a `dipole supersolid'. While this supersolid state may eventually be unstable against lattice effects in the thermodynamic limit, its numerical robustness is remarkable. We discuss potential experimental implications of our results. |
Thursday, March 9, 2023 10:48AM - 11:00AM |
S65.00015: Bose-Hubbard triangular ladder in an artificial gauge field Catalin-Mihai Halati, Thierry Giamarchi We consider interacting bosonic particles on a two-leg triangular ladder in the presence of an artificial gauge field. We employ density matrix renormalization group numerical simulations and analytical bosonization calculations to study the rich phase diagram of this system. We show that the interplay between the frustration induced by the triangular lattice geometry and the interactions gives rise to multiple chiral quantum phases. Phase transition between superfluid to Mott-insulating states occur, which can have Meissner or vortex character. Furthermore, a state that explicitly breaks the symmetry between the two legs of the ladder, the biased chiral superfluid, is found for large values of the flux. In the regime of hardcore bosons, we show that the extension of the bond order insulator beyond the case of the fully frustrated ladder exhibits Meissner-type chiral currents. |
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