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 X07: Elementary Excitations and Solitons in Cold Atomic Gases |
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Chair: Peter Engels, Washington State University Room: 206 B |
Friday, June 9, 2023 8:00AM - 8:12AM |
X07.00001: Deterministic creation and detection of vortices in molecular Bose-Einstein condensates Shu Nagata, Youjia Huang, Tzu-Ken Shen, Jay Jachinowski, Cheng Chin Quantum vortices are characterized by the phase winding of the macroscopic wavefunction around the annulus. When two atoms are paired into a diatomic molecule, the phase of the molecule is expected to be double that of the atom. Past studies have indicated new types of vortex states in coupled atomic-molecular Bose-Einstein condensates (BECs). In this work, we deterministically create and manipulate vortices by translating two blue-detuned laser beams in an atomic BEC. Pairs of vortices with opposite circulation are generated by the motion of the beams with each vortex pinned to the position of the laser beam. We subsequently leave one vortex in the BEC and drag the other one out of the BEC. We detect the vorticity by interfering the BEC with a vortex with another BEC with no vortex. We also apply this technique to a Cs2 molecular BEC containing vortices and test the prediction of phase doubling in the pairing processing. |
Friday, June 9, 2023 8:12AM - 8:24AM |
X07.00002: A rotating bucket experiment with Bose-Einstein condensate Ruixiao Yao, Sungjae Chi, Airlia Shaffer, Richard J Fletcher, Martin W Zwierlein Quantized vortices, found in rotating liquid helium, quantum gases, and Type-II superconductors, have attracted ongoing attention from across mathematics and physics. An extraordinarily rich phase diagram for quantum vortex matter has been proposed, exhibiting for instance lattice, liquid, glass, and phases. Especially in the lowest Landau level, the positions of vortices realize complex zeros of random polynomials. Here we report the realization of a "rotating bucket" experiment using a rapidly-rotating Bose-Einstein condensate confined by a cylindrical optical wall potential. Upon balancing the centrifugal force and underlying trapping force in the rotating frame, the condensate exhibits a flat density profile and a proliferation of quantum vortices in its bulk. We experimentally realize a homogeneous, isotropic vortex liquid phase, demonstrate that the vortex density fully satisfies the Feynman’s criterion, and show intriguing statistics in the vortex-vortex correlations originated from their pair-wise interaction. |
Friday, June 9, 2023 8:24AM - 8:36AM |
X07.00003: Conformal duality of Bose-Einstein condensates with two- and three-body interactions David B Reinhardt, Matthias Meister, Dean Lee, Wolfgang P Schleich Solitary waves and droplets are intriguing phenomena that fundamentally rely on the nonlinear atom-atom interactions of Bose-Einstein condensates (BECs). Remarkably, in the quasi-one dimensional case analytical solutions exist for the cubic nonlinear Schrödinger equation used to describe BECs with two-body interactions [1]. However, new solution types emerge when we consider higher-order interactions such as three-body interactions. Here, we show that the cubic-quintic nonlinear Schrödinger equation exhibits a unique correspondence to its lower-order counterpart in terms of a conformal duality. By means of this duality we relate the densities and the velocity fields of Bose-condensed systems with and without three-body interactions allowing us to determine the properties of a BEC by means of its conformal partner with corresponding higher- or lower interaction order. We explain the origin, present some applications and show the generalization to arbitrary high-order scattering processes within the mean field regime including the case of the non-interacting linear Schrödinger equation. Finally, we discuss the applicability of the conformal duality to higher-dimensional systems. |
Friday, June 9, 2023 8:36AM - 8:48AM |
X07.00004: Experimental realization of Peregrine solitons in a Bose-Einstein condensate Peter W Engels, Alejandro Romero-Ros, Lia Katsimiga, Simeon I Mistakidis, Peter Schmelcher, Gino Biondini, Sean Mossman, Panayotis Kevrekidis Solitons are a hallmark phenomenon of nonlinear dynamics. While a diverse variety of solitons has been considered in physical realizations including BECs, water tanks, optical fibers, plasmas, magnetic materials and more, an intriguing new addition to the family of solitons was found in 1983 by the theoretical discovery of Peregrine solitons as a dynamic solution of the nonlinear Schrödinger equation. These solutions localize in space and time: they emerge out of a background, form a large, pronounced peak, and vanish, making them candidates for possible explanations of rogue waves. This discovery has created a lot of excitement, but their experimental realization has only recently been successful using optical fibers and large water wave tanks. |
Friday, June 9, 2023 8:48AM - 9:00AM |
X07.00005: Ultrawide dark solitons in ultracold Bose systems with competing interactions Jakub Kopycinski, Maciej Lebek, Luca Parisi, Wojciech Górecki, Nick Parker, Krzysztof Pawlowski We investigate the behavior of dark solitons in two types of one-dimensional ultracold systems: dipolar bosons and Bose-Bose mixtures. In both systems, there are two types of interactions - a long-range attractive interaction and a repulsive contact interaction in the former. In the latter - attractive intercomponent and repulsive intracomponent interactions. By combining hydrodynamics and ab initio models, we extend the understanding of dark solitons beyond the Gross-Pitaevskii equation. Our equations have different types of nonlinearities, leading to novel results. Our findings show that at a critical interaction strength, the solitons broaden significantly, exhibiting an unconventional dispersion relation, and lacking the typical phase jump and zero minimum density features of stationary solitons. This behavior is universal across both dipolar atoms and mixtures. Our results also suggest that these solitons may exist within quantum droplets. |
Friday, June 9, 2023 9:00AM - 9:12AM |
X07.00006: Dynamics of polaron formation in weakly interacting 1D Bose gases Martin Will, Michael Fleischhauer In recent years much research has been devoted to understand the ground-state properties of Bose polarons, quasiparticles composed of mobile impurities surrounded by a degenerate Bose gas. However, many questions regarding their dynamics remained open. Here we present a detailed study of the time evolution of an impurity injected into a one-dimensional Bose gas, either homogeneous or harmonically trapped. The system is analyzed in a mean-field approach that accounts for the backaction to the condensate and goes beyond the standard Froehlich model, complemented with Truncated Wigner simulations to include quantum fluctuation. We find a rich scenario of dynamical regimes including deceleration or even backscattering caused by the emission of density waves or solitons. Due to the formation of the polaron, the impurity is slowed down even when initially slower than the Landau critical velocity. Under certain conditions the system does not evolve into the polaron ground state, but rather into a metastable excited one, corresponding to the trapping of a soliton at the position of the impurity. We analyze quantum fluctuations in the trapped system and show under what conditions their influence can be made small. |
Friday, June 9, 2023 9:12AM - 9:24AM |
X07.00007: A Rydberg impurity in an ideal Bose-Einstein condensate Matthew T Eiles, Aileen Durst The excitation of a Rydberg atom in an ideal Bose-Einstein condensate (BEC) leads to a generalization of the paradigmatic Bose polaron. While the interaction between ground-state atoms is short-ranged in nature and can be replaced by a contact pseudopotential, this cannot be done in general for a Rydberg impurity, whose interaction range typically surpasses the mean interparticle spacing in the bath. Furthermore, this interaction can support several deeply bound two-body molecular states. These features of the Rydberg impurity complicate its theoretical description and analysis and cause it to exhibit a host of new behaviors not seen in the simpler system of a ground-state impurity in an ultracold gas. By computing the absorption spectrum, we map out the phase diagram of the Rydberg impurity in a BEC. We see evidence for both attractive and repulsive polaron branches, where the Rydberg atom is dressed by excitations of the surrounding bath, in addition to a many-body bound state characterized by the attachment of many atoms to the impurity. The latter scenario has been experimentally observed already, and we propose regimes where the quasiparticle branches, or their effects, can be similarly observed. |
Friday, June 9, 2023 9:24AM - 9:36AM |
X07.00008: Bose Polarons in a Homogenous Bose-Einstein Condensate Jiri Etrych, Alec Cao, Gevorg Martirosyan, Christopher Ho, Zoran Hadzibabic, Christoph Eigen We study Bose polarons in a homogeneous BEC of 39K atoms, produced in an optical-box trap. The impurities are formed using rf-injection between spin states, and the interstate interactions are tuned using magnetic Feshbach resonances. Leveraging the suppression of inhomogeneous broadening in a box-trapped gas, we use a combination of injection spectroscopy and Ramsey-like many-body interferometry to access the injection spectrum (frequency domain) and the impurity-coherence function (time domain) for both attractive and repulsive interactions. On the repulsive side of the resonance, we resolve two energy branches, corresponding to a repulsive polaron and a many-body state connected to the Feshbach dimer, whose energy shifts with density. Finally, we obtain first measurements of the Bose-polaron quasiparticle residue using the many-body interferometry. |
Friday, June 9, 2023 9:36AM - 9:48AM Withdrawn |
X07.00009: Non-Gaussian quantum correlations in many-body bound states of Bose polarons Nader Mostaan, Nathan Goldman, Fabian Grusdt A mobile impurity resonantly coupled to a Bose-Einstein Ccondensate (BEC) forms a quasiparticle termed Bose polaron. Understanding the physical properties of Bose polarons can provide crucial insights into the formation of few-to-many body quantum correlations in Bose-condensed systems. In cold atom realizations of Bose polarons, the impurity-boson interaction strength is tunable via Feshbach resonances, allowing access to interaction regimes beyond the capacity of conventional solid-state platforms. In the strong-coupling regime, the impurity can induce an unstable Bogoliubov mode causing an indefinite cascaded decay of the BEC. We show that the interplay of impurity-induced instability and stabilization by repulsive inter-boson interactions results in a discrete set of bound-states at intermediate energies between attractive and repulsive polaron branches. These states demonstrate strong non-Gaussian correlations, requiring non-perturbative beyond-mean field treatments for their characterization. Furthermore, they exhibit vanishing quasiparticle residue and thus are inaccessible by conventional impurity spectroscopy techniques. Nevertheless, we show that they have observable signatures in molecular spectroscopy- based detection techniques. |
Friday, June 9, 2023 9:48AM - 10:00AM Withdrawn |
X07.00010: Radiofrequency Spectroscopy of Bose Polarons with Strong Final State Interactions Alexander Chuang, Carsten Robens, Yiqi Ni, Eric Wolf, Yiming Zhang, Arthur Christianen, Richard Schmidt, Martin W Zwierlein The fate of impurities immersed in a quantum bath is a fundamental problem in many-body physics. In experiments on Bose-Fermi mixtures of Na-40K we have previously observed the formation of Bose polarons, impurity atoms strongly coupled to a Bose-Einstein condensate [1]. The nature of these polarons and their excitations in the case where a two-body bound state is supported by the interatomic potential is not well understood. We study this energy landscape by starting with a more weakly coupled Bose polaron and exploring the final states it can be coupled to via radiofrequency spectroscopy . We choose the final spin of the impurity such that the impurity-boson scattering length is positive, and thus supports two-body bound states (i.e. heteronuclear Feshbach molecules). We find that two-body physics is insufficient to explain our spectra, and instead reveal many-particle correlations between the impurity and the host bosons. [1] Z. Z. Yan, Y. Ni, C. Robens, and M. W. Zwierlein, Science 368, 190 (2020).
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