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 E04: Dynamics of Cold Atoms in Optical Lattices IILive
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Chair: Annabelle Bohrdt, Tech Univ Muenchen |
Tuesday, June 1, 2021 2:00PM - 2:12PM Live |
E04.00001: Localization of composite quantum particles in a random potential Fumika Suzuki, Mikhail Lemeshko, Wojciech H Zurek, Roman Krems We investigate the effect of coupling between translational and internal degrees of freedom of composite quantum particles on their localization in a random potential. We show that entanglement between the two degrees of freedom weakens localization due to the upper bound imposed on the inverse participation ratio by purity of a quantum state. We perform numerical calculations for a two-particle system bound by a harmonic force in a 1D disordered lattice and a rigid rotor in a 2D disordered lattice. We illustrate that the coupling has a dramatic effect on localization properties, even with a small number of internal states participating in quantum dynamics. |
Tuesday, June 1, 2021 2:12PM - 2:24PM Live |
E04.00002: Pair Correlations and Photoassociation Dynamics of Two Atoms in an Optical Tweezer Marvin Weyland, Stuart Szigeti, Rhys Hobbs, Poramaporn Ruksasakchai, Lucile Sanchez, Mikkel F Andersen New techniques for individual atom preperation allow investigations of photoassociation using exactly two atoms, giving much better control over the process and the created molecule. We prepare exactly two Rb-85 atoms in the same internal state in an optical tweezer and photoassociate them. |
Tuesday, June 1, 2021 2:24PM - 2:36PM Live |
E04.00003: Multiband Features in Matter-Wave Decay Alfonso Lanuza, Joonhyuk Kwon, Youngshin Kim, Dominik Schneble Experiments with ultracold atoms in state-selective optical lattices allow for the simulation of spontaneous emission of single quanta [1, 2], a phenomenon that traditionally was exclusive to quantum optics. The multiband structure of the lattice in which a quantum of radiation is emitted can have dramatic effects on the characteristics of the emission/decay process. When the quantum is repeatedly reabsorbed and reemitted by an emitter array, a more complex band structure arises altogether. We present a way to model these multiband effects and compare them with the experiments. |
Tuesday, June 1, 2021 2:36PM - 2:48PM Live |
E04.00004: Unraveling fractionalized excitations with time-dependent ARPES in quantum gas microscopes Alexander Schuckert One of the most illusive features of the cuprates is the missing spectral weight of electrons measured in angle-resolved-photoemission spectroscopy (ARPES) beyond the so-called Fermi arcs. It has been proposed that a fractionalization of the electron into spinon and chargon might explain this phenomenon by a formation of a spinon Fermi sea, indicative of a quantum spin liquid. However, evidence for this conjecture remains scarce. Here, we propose to directly transfer spectral weight of spinons to states which are unoccupied in the ground state by strong magnetic field gradient pulses. We demonstrate our protocol in a one-dimensional t-J model, where we show that the whole spinon dispersion can be imaged by time-dependent ARPES after applying the gradient. Long-lived coherent oscillations are visible in the spectrum, which we explain by beyond mean-field interactions between spinons. Moving to the two-dimensional tJ model relevant for the cuprates, we recover spectral weight at low frequencies in two spatial dimensions, indicating that our protocol might lead to a more complete understanding of Fermi arcs. As our protocol is challenging to achieve in the solid state, we show how to implement time dependent ARPES in quantum gas microscopes, opening up the possibility to directly compare pump-probe experiments on cuprates and quantum simulators of the Hubbard model. Our work paves the way to studying emergent fractionalized excitations via non-equilibrium probes in quantum gas microscopes. |
Tuesday, June 1, 2021 2:48PM - 3:00PM Live |
E04.00005: Dynamical localization in periodically kicked 1D bichromatic optical lattices Toshihiko Shimasaki, Peter Dotti, Max Prichard, Alec J Cao, Jared E Pagett, David M Weld We report experimental studies of localization in one-dimensional periodically kicked incommensurate optical lattices as proposed in [1]. In these experiments a secondary incommensurate lattice is periodically pulsed, creating a temporally periodic but spatially quasiperiodic modulation on a primary translation-symmetric optical lattice potential. In agreement with theoretical predictions, we observe a transition between localized and delocalized phases which depends on both kick strength and kick period. At large kick periods higher-band effects cause deviations from tight-binding theoretical predictions, but these effects are non-monotonic in kick period and can be suppressed by choosing the drive waveform appropriately. We describe possible applications in Floquet engineering, and experimentally investigate the consequence of temporal aperiodicity in the secondary lattice pulses [2]. |
Tuesday, June 1, 2021 3:00PM - 3:12PM Live |
E04.00006: Transport controlled by Poincaré orbit topology in a driven inhomogeneous lattice gas Alec J Cao, Roshan Sajjad, Ethan Q Simmons, Coraline Fujiwara, Toshihiko Shimasaki, David M Weld In periodic quantum systems which are both homogeneously tilted and driven, the interplay between drive and Bloch oscillations controls transport dynamics. Using a quantum gas in a modulated optical lattice, we show experimentally that inhomogeneity of the applied force leads to a rich variety of dynamical behaviors controlled by the drive phase, from self-parametrically-modulated Bloch epicycles to adaptive driving of transport against a force gradient to modulation-enhanced monopole modes. By examining Poincaré portraits of the semiclassical transport equations, we demonstrate that the observed dynamics reflect the rich topological structure of stroboscopic orbits on a Brillouin phase-space cylinder. |
Tuesday, June 1, 2021 3:12PM - 3:24PM Live |
E04.00007: Signatures of bath-induced quantum avalanches in a many-body–localized system Sooshin Kim, Julian Léonard, Matthew Rispoli, Alexander Lukin, Robert Schittko, Joyce Kwan, Dries Sels, Eugene Demler, Markus Greiner Many-body localization has been established as a robust exception of thermalization, yet its fate remains unclear when being brought in contact with a thermal inclusion. We realize a many-body-localized system coupled to a thermal inclusion of different size and study its dynamics. We observe accelerated transport from the inclusion to the localized system, driven by a quantum avalanche propagating through the localized system. To investigate how the avalanche develops, we probe the single-site entropy and study the thermalization of the system. Moreover, multipoint correlations between the inclusion and the localized system are evaluated to look for the existence of high-order process. Our study presents interesting signals regarding the stability of many-body-localized systems and their critical behavior. |
Tuesday, June 1, 2021 3:24PM - 3:36PM Live |
E04.00008: Emergence of an unconventional Bose-Einstein condensate in higher orbitals of a hexagonal lattice Alexander Ilin, Tobias Klafka, Klaus Sengstock, Juliette Simonet Atoms in higher lattice orbitals provide new possibilities for realizing exotic quantum many-body states without an analogue in traditional condensed matter systems. In our experiment, we drive a bosonic ensemble of cold atoms in a bipartite hexagonal lattice into a non-equilibrium state by a rapid quench of the sublattice energy offset. The subsequent dynamics reveal the emergence of coherence and long-range order in higher orbital states and the evolution to an unconventional Bose-Einstein condensate in the two degenerate minima Κ and Κ′ of the second Bloch band. Numerical simulations indicate that atoms remaining in the first Bloch band support the condensation by acting as an efficient heat sink. Final temperature and interactions critically influence the nature of the resulting superfluid, which can be either fragmented or in a coherent superposition at Κ and Κ′. |
Tuesday, June 1, 2021 3:36PM - 3:48PM On Demand |
E04.00009: Atom number distributions after quantum quenches in lattice-confined spinor gases Jared O Austin, Zachary N Shaw, Zihe Chen, Khan Mahmud, Yingmei Liu We present an experimental study on atom number distributions of lattice-confined spinor gases after well-engineered quantum quenches across superfluid to Mott insulator phase transitions. As the lattice quench speed decreases, our data reveal that the fraction of atoms in even Mott lobes initially has a large value and then quickly drops before slowly approaching the distributions predicted for adiabatic ramps. This work demonstrates a potential method of maximizing the fraction of atoms in even Mott lobes which, among other things, may enable future works to optimize the production of spin singlets in lattice confined ultracold atoms. |
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