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 H07: Dipolar BECs |
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Chair: Matt Grau, Old Dominion University Room: 206 B |
Wednesday, June 7, 2023 8:00AM - 8:12AM |
H07.00001: Observation of vortices and vortex stripes in a dipolar BEC of magnetic atoms Eva Casotti, Lauritz Klaus, Thomas Bland, Elena Poli, Claudia Politi, Giacomo Lamporesi, Russell N Bisset, Manfred J Mark, Francesca Ferlaino Quantized vortices are one of the hallmarks of superfluidity and have been observed in numerous systems from liquid helium to quantum fluids of light, from superconductors to contact-interacting Bose-Einstein condensates (BECs). Here, we report on the first experimental observation of vortices in a strongly magnetic BEC of Dysprosium atoms, characterized by anisotropic long-range interaction. Unlike alkali atoms, which require complex techniques to impart angular momentum to the atomic cloud, dipolar quantum gases offer a unique opportunity. Following a new concept proposed in 2019, we are able to rotate the gas by revolving the magnetic field axis. Due to the phenomenon of magnetostriction, tilting the magnetic field towards the radial plane breaks the cylindrical symmetry of the cloud, which can then be set into rotation. We show that when the critical velocity is reached the system starts to nucleate vortices. We also observe one of the first predictions for vortices in presence of dipolar interaction: their rearrangement into stripes along the magnetic field direction. This new technique can be generalized to any quantum phase of dipolar gases, including the paradoxical supersolid phase, which still awaits direct observation of the superfluid irrotational properties. |
Wednesday, June 7, 2023 8:12AM - 8:24AM |
H07.00002: Realization of a quasi-two dimensional dipolar Bose gas Ziting Chen, Yifei He, Mingchen Huang, Mithilesh K Parit, Haoting Zhen, Gyu-Boong Jo Lanthanide atoms with a large magnetic dipole moment, such as erbium and dysprosium, have attracted significant attention in quantum simulation benefitting from strong dipole-dipole interactions. Such long-ranged and anisotropic interaction gives rise to novel quantum states including quantum droplets and dipolar supersolids. However, while many predictions have been made on quasi-two dimensional dipolar Bose gases, such as anisotropic excitation spectrum and anisotropic coherence properties of superfluid, to date, experimental realization remains challenging. Here, we present the realization of quasi-two-dimensional dipolar Bose gas of erbium, where tight confinement is provided by an optical sheet trap and kinematically two-dimensional conditions are satisfied. To assess two-dimensional superfluidity arising from the Berezinsky-Kosterlitz-Thouless transition, we systematically monitor the momentum information of the sample by means of a momentum-focusing technique. Preliminary results will be discussed. |
Wednesday, June 7, 2023 8:24AM - 8:36AM |
H07.00003: Observation of superradiant light scattering from a phase fluctuating dipolarBose-Einstein condensate Mingchen Huang, Bojeong Seo, Ziting Chen, Mithilesh K Parit, Yifei He, Haoting Zhen, Gyu-Boong Jo Collective light scattering in a Bose-Einstein condensate (BEC) has been extensively studied by |
Wednesday, June 7, 2023 8:36AM - 8:48AM |
H07.00004: Dipole condensation Wenhui Xu, Chenwei Lv, Qi Zhou Whereas bosons tend to condense at low temperatures, they may form condensates in unconventional means. Here, we show that various bosonic systems exhibit dipole condensation, namely particle-hole pairs instead of single particles form a condensate. By tuning the microscopic parameters, the phases of dipole condensates can be controled to access a new class of macroscopic quantum phenomenon. |
Wednesday, June 7, 2023 8:48AM - 9:00AM |
H07.00005: Measuring the dipolar interaction shift of the BEC critical temperature Milan Krstajic, Lucas R Hofer, Jiří Kučera, Péter Juhász, Gavin Lamb, Robert P Smith The effect of dipolar interactions on harmonically trapped BECs has been the subject of intense and fruitful research over recent years, but despite being theoretically calculated over 15 years ago [1] the modification of the BEC transition temperature due to dipole-dipole interactions has, up to now, not been experimentally observed. We will present our experimental findings on this topic; using an ultracold erbium gas confined in a highly prolate trap we directly observe the dependence of the critical temperature on the orientation of the dipoles relative to the trap. |
Wednesday, June 7, 2023 9:00AM - 9:12AM |
H07.00006: Characterisation of three-body loss in ultracold 166Er and the production of large dipolar Bose–Einstein condensates Milan Krstajic, Jiri Kucera, Péter Juhász, Lucas R Hofer, Gavin Lamb, Anna L Marchant, Robert P Smith Dipolar quantum droplets and supersolids are subject to intense research. However, studies are often limited by the achievable atom numbers and hindered by high three-body loss rates. In this talk, we present our study of density-dependent atom loss in an ultracold gas of 166Er, identifying several previously unknown features which display a strong temperature dependence. We use the detailed knowledge of the loss landscape to produce dipolar Bose–Einstein condensates with more than 2×105 atoms, pointing towards optimal strategies for the study of large-atom-number dipolar gases in the droplet and supersolid regimes. |
Wednesday, June 7, 2023 9:12AM - 9:24AM |
H07.00007: Properties of Dipolar Impurities in a Dipolar Medium Neelam Shukla, Artem G Volosniev, Jeremy R Armstrong Relaxation dynamics in closed quantum systems are responsible for some of the most difficult issues in many-body physics. Understanding these dynamics is crucial for quantum statistical physics, but it is also an open question in many other disciplines, such as cosmology, quantum information, and high-energy physics [1]. An ideal model to answer those problems is an impurity interacting with a quantum environment. A dipole with at least one different property from the medium, such as a distinct hyperfine state, mass, or dipole moment, would be referred to as a dipolar polaron. All the dipole moments are aligned along the z-axis by an external field. The polaron-dipolar gas system could exhibit attractive and repulsive interactions depending on the direction as the dipole-dipole interaction is anisotropic and long-range. As a result, we have investigated and calculated the many characteristics of this impurity in both two (2D) and three (3D) dimensional environments. For this purpose, we used the split-step Crank-Nicolson method to solve the modified Gross-Pitaevskii (GP) equation. 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. Additionally, these results are calculated for different angles, i.e., the angle between the system’s dipoles and the dipolar polaron impurity. We also determined the impurity-impurity interaction energy as a function of impurity strengths by adding another impurity to the system. The GP equation incorporating temporal dynamics was then solved in three dimensions using one impurity. We deduced from the results that the system exhibits anisotropic response in quench dynamics after the addition of the impurity. |
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