Bulletin of the American Physical Society
52nd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 66, Number 6
Monday–Friday, May 31–June 4 2021; Virtual; Time Zone: Central Daylight Time, USA
Session E06: Cold and Ultracold Multielectron AtomsLive
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Chair: Dan Stamper-Kurn, UC Berkeley |
Tuesday, June 1, 2021 2:00PM - 2:12PM Live |
E06.00001: Quantum droplets of dipolar mixtures Russell Bisset, Luis Peña Ardila, Luis Santos Self-bound quantum droplets can emerge in either two-component or dipolar Bose-Einstein condensates (BECs), where stability is crucially provided by quantum fluctuations. Motivated by recent experiments producing BEC mixtures of highly-magnetic erbium and dysprosium atoms [PRL 121, 213601 (2018)], we develop a theoretical description of two-component dipolar BECs that includes Lee-Huang-Yang quantum fluctuations [PRL 126, 025301 (2021)]. While non-dipolar self-bound mixtures are necessarily miscible with an approximately fixed ratio between the two densities, the density ratio for dipolar mixtures is free, presenting novel and significantly richer physics. We predict that a self-bound immiscible droplet should be possible due to mutual non-local attraction, resulting in the formation of a droplet molecule. Moreover, our analysis of strongly imbalanced populations shows that quantum fluctuations in the majority component crucially modify the miscibility of impurities. Our work opens intriguing perspectives for the exploration of spinor physics in ultra-dilute liquids, which should resemble to some extent 4He-3He droplets and impurity-doped helium droplets. |
Tuesday, June 1, 2021 2:12PM - 2:24PM Live |
E06.00002: Rotating Dipolar Bose-Einstein Condensates in Tilted Reference Frames Srivatsa B Prasad, Andrew Martin, Brendan Mulkerin Rotating Bose-Einstein condensates (BECs) have long been of considerable interest, especially in the context of the study of quantum vortices and quantum turbulence. For species with large dipole moments, there is also the possibility of effectively tuning the time-averaged dipolar interaction through rapidly rotating the dipole polarization. To date, most investigations have assumed that the rotation axis is parallel to one of the condensate's principal axes. In this talk, we present our recent theoretical investigation of a harmonically trapped dipolar BEC with its rotating dipole moments tilted arbitrarily about the rotation axis. We show that the co-rotating Thomas-Fermi (TF) stationary state density is tilted nontrivially about the trap as well as both the polarization and rotation axes at finite rotation frequencies. These stationary states also agree with those obtained by time-averaging the dipolar interaction at rapid rotation frequencies. However, we find that the TF state is dynamically unstable in this regime, which may explain deviations from the time-averaged theory in recent experiments (Tang, et al., 2019) and also raise the possibility of detecting novel vortex lattice phases in dipolar BECs. |
Tuesday, June 1, 2021 2:24PM - 2:36PM Live |
E06.00003: Efficient creation of dipolar 168Er Bose-Einstein condensates for quantum simulation Bojeong Seo, Ziting Chen, Mingchen Huang, Mithilesh Parit, Peng Chen, Gyu-boong Jo Lanthanide atoms such as erbium and dysprosium, are excellent systems for the study of quantum many-body physics due to their considerable magnetic moment from the large angular momentum. To explore such a dipolar system, we create degenerate erbium quantum gases in a newly developed apparatus, in which diverse cold-atom toolkits including a narrow-line optical transition, a Feshbach resonance, and a metastable excited state are easily available. I will discuss how we efficiently prepare degenerate dipolar quantum gases of 168Er using the two-stage slower followed by the evaporative cooling in a crossed dipole trap, as well as on-going experiments with dipolar atoms. |
Tuesday, June 1, 2021 2:36PM - 2:48PM Live |
E06.00004: Density Fluctuations across the Superfluid-Supersolid Phase Transition in a Dipolar Quantum Gas Mingyang Guo, Jens Hertkorn, Jan-Niklas Schmidt, Fabian Boettcher, Matthias Schmidt, Kevin Ng, Hans Peter Büchler, Tim Langen, Martin W Zwierlein, Tilman Pfau Fluctuations are crucial to gain insights into phase transitions and elementary excitations. Here we report direct in situ measurement of the density fluctuations across the phase transition from a dipolar Bose-Einstein condensate to the supersolid state. This allows us to image the spatial pattern of the roton modes, which are the dominant contribution to the fluctuation and induce the phase transition. The extracted static structure factor features an increasing peak while approaching the transition point and reaches the maximum at the critical point, resulting from the enhanced population of the roton modes as they soften. Thermal fluctuations due to the finite temperature further enhances the static structure factor, giving rise to almost a factor of hundred compared to the zero-temperature case. On the supersolid side, the simultaneous observation of the BEC and crystal phonons is a hallmark for supersolidity. |
Tuesday, June 1, 2021 2:48PM - 3:00PM Live |
E06.00005: Stability of a purely dipolar gas in a power-law potential Péter Juhász, Milan Krstajic, David Strachan, Edward Gandar, Robert Smith We solve the time-independent Gross–Pitaevskii equation numerically to explore the stability of a purely dipolar Bose–Einstein condensate (BEC) in a cylindrically-symmetric trap. The atoms are polarised and confined to a harmonic potential along the cylinder’s axis, and they are trapped in a general power-law potential (rn) in the perpendicular direction. We explore the effect of both the power law and the trap aspect ratio. |
Tuesday, June 1, 2021 3:00PM - 3:12PM Live |
E06.00006: Towards an erbium Bose-Einstein Condensate in an optical box potential Milan Krstajic, Peter Juhász, Lucas Hofer, Anna Marchant, Jiří Kučera, Robert Smith We report our progress towards producing a Bose-Einstein condensate (BEC) of dipolar erbium atoms in an optical box potential. Our cooling protocol closely follows existing methods - a narrow line magneto-optical trap (MOT) is loaded using a Zeeman-slowed atomic beam, followed by transfer of atoms to an optical dipole trap and subsequent evaporation and transport to an all-glass cell with enhanced optical access. Here, the atoms will be confined in a quasi-2D optical box trap generated using a spatial light modulator which will readily allow modification of both the size and shape of the potential. In parallel, the experiment is being expanded to add potassium as a second atomic species which would open possibilities to research impurity physics, Bose polarons and open quantum systems more generally. |
Tuesday, June 1, 2021 3:12PM - 3:24PM Live |
E06.00007: Two-photon Resolved-Sideband Raman Cooling of171Yb in an optical cavity. Simone COLOMBO Atomic collision is an essential ingredient to cool trapped clouds to ultracold temperatures via an evaporative cooling process. Without it, such as the cases of cooling optical-lattice clock atoms like 171Yb and 88Sr, it is rather challenging to reach such low temperatures. |
Tuesday, June 1, 2021 3:24PM - 3:36PM Live |
E06.00008: Analysis of Stimulated Forces for Slowing and Trapping Yb Atoms on the Narrow 1S0 ↔ 3P1 Transition T. N Na Narong, L. Hollberg Ytterbium based optical atomic clocks, degenerate gases, optical lattices, and tweezers for quantum measurements rely on Yb atoms cooled and trapped in a 556 nm MOT on the 1S0 ↔ 3P1 transition. The conventional approach requires two stages of cooling to achieve a high loading rate and temperatures in the μK range and uses both the broad 1S0 ↔ 1P1 (399 nm, 28 MHz), and narrow (556 nm,182 kHz) transitions. To simplify the cooling and trapping system from using two lasers to one, we propose a method for slowing, cooling and trapping Yb atoms using stimulated forces and only the narrow 1S0 ↔ 3P1 transition. |
Tuesday, June 1, 2021 3:36PM - 3:48PM Live |
E06.00009: Clock-mediated laser cooling on the meta-stable state in a 1D optical lattice clock ChunChia Chen, William McGrew, Jacob Siegel, Xiaogang Zhang, Youssef Hassan, Kyle P Beloy, Andrew Ludlow Optical lattice clocks have demonstrated unprecedented performance below the 10−18 fractional level [1], towards new standards of time and sensitive probes in fundamental physics. Here, we report on a novel cooling scheme on the excited meta-stable 3P0 state in a 1D 171Yb optical lattice clock. The Sisyphus cooling scheme operates by dressing the clock state with a standing wave that connects to a higher lying excited state[2], and is mediated by excitation on the clock transition. This cooling technique can be useful for the efficient loading of shallow lattices, which in turn help reduce systematic clock shifts from the trap itself to the 10−19 level and below. |
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