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 K07: Transport Dynamics in Cold Atom SystemsLive
|
Hide Abstracts |
Chair: Shizhong Zhang, Hong Kong University |
Wednesday, June 2, 2021 10:30AM - 10:42AM Live |
K07.00001: SU(1, 1) echoes for breathers in quantum gases Chenwei Lv, Ren Zhang, Qi Zhou Though the celebrated spin echoes have been widely used to reverse quantum dynamics, they are not applicable to systems whose constituents are beyond the control of the su(2) algebra. Here, we design echoes to reverse quantum dynamics of breathers in three-dimensional unitary fermions and two-dimensional bosons and fermions with contact interactions, which are governed by an underlying su(1,1) algebra. Geometrically, SU(1,1) echoes produce closed trajectories on a single or multiple Poincare disks and thus could recover any initial states without changing the sign of the Hamiltonian. In particular, the initial shape of a breather determines the superposition of trajectories on multiple Poincare disks and whether the revival time has period multiplication. Our work provides physicists with a recipe to tailor collective excitations of interacting many-body systems. |
Wednesday, June 2, 2021 10:42AM - 10:54AM Live |
K07.00002: Interaction-induced dynamics of collective atomic excitations Yefeng Mei, Yin Li, Huy N Nguyen, Paul R Berman, Alexander M Kuzmich The dephasing dynamics of collective Rydberg excitations are investigated for atoms confined in a state-insensitive optical lattice. By measuring the second-order correlation function, g(2), as a function of storage time, we observe a characteristic decrease of g(2) that is found to be in agreement with a model based on the dephasing of multiple excitations resulting from van der Waals interactions. |
Wednesday, June 2, 2021 10:54AM - 11:06AM Live |
K07.00003: Topological pump of ultracold fermions in a one dimensional shaken optical lattice Joaquin Minguzzi, Kilian Sandholzer, Anne-Sophie Walter, Zijie Zhu, Konrad G Viebahn, Tilman Esslinger Topological pumps allow quantized transport of particles in periodic potentials, in which external parameters are varied in a slow, cyclic manner. Their topological origin is analogous to the quantum Hall effect, in that the amount of transported charge is robust against perturbations and does not depend on the specific pumping protocol. In atomic physics, ultracold atoms in optical lattices are versatile systems to observe such topological effects. So far, charge pumping has been achieved in dynamically controlled bipartite optical lattices, which operate in a regime where atoms adiabatically follow the cyclically deformed lattice potential. Here, we experimentally realize a topological pump of ultracold spin-polarized fermions in a simple one dimensional optical lattice. The experiment consists in resonantly shaking an optical lattice to prepare the fermions in a hybridized orbital, which endows the atomic cloud with a non-centrosymmetric charge polarization. Pumping is subsequently achieved by periodically modulating the shaking waveform slow enough to ensure adiabaticity. In contrast to previous experiments, which have been based on the Rice-Mele model, our measurements are consistent with the fully connected Creutz-ladder Hamiltonian. These results pave the way for studying topological pumping in the interacting regime. |
Wednesday, June 2, 2021 11:06AM - 11:18AM Live |
K07.00004: Glassy dynamics in a disordered Heisenberg quantum spin system Clement Hainaut, Annika Tebben, Titus Franz, Andre Salzinger, Gerhard Zuern, Martin Gärttner, Sebastian Geier, Philipp Schultzen, Matthias Weidemuller, Shannon Whitlock, Adrien Signoles The macroscopic nature of many-body systems is drastically changed by the presence of disorder in the medium which might induce new phases of matter like Spin glasses or Localization. We report on dynamics of an ultracold Rydberg gas which realizes a disordered quantum spin system. Here the role of disorder is particularly intriguing, giving rise to anomalously slow dynamics characterized by a stretched exponential function analogous to classical glasses. We find the characteristic exponent to be independent of the strength of disorder up to a critical value suggesting that slow dynamics is a generic property of disordered quantum spin systems |
Wednesday, June 2, 2021 11:18AM - 11:30AM Live |
K07.00005: Evolution of Attractive Bose Polarons Near a Feshbach Resonance Yiqi Ni, Alexander Chuang, Eric Wolf, Carsten Robens, Martin W Zwierlein We investigate how Bose polarons asymptotically evolve into Feshbach molecules as a function of interaction strength. We create Bose polarons by immersing fermionic impurities in a Bose-Einstein condensate. Using spatially resolved RF spectroscopy, we probe the energy and spectral width of the transition from an initial attractive polaron on the attractive side of the resonance, to three different final states, repulsive polaron, Feshbach molecule, and attractive polaron on the repulsive side of the resonance. We observe the attractive polaron to smoothly crossover into a Feshbach molecule. Multi-phonon resonances predicted in some theoretical predictions are not observed. The smooth connection between polarons and Feshbach molecules also opens up pathways for direct photoassociation of free polarons into more tightly bound molecules. |
Wednesday, June 2, 2021 11:30AM - 11:42AM Live |
K07.00006: Transport in the Presence of an Effective Range: Comparing the Shear and Bulk Viscosities Jeff A Maki, Shizhong Zhang The transport properties of atomic gases depend sensitively on the scattering between individual particles. These interactions are described, to the lowest order, by an energy independent constant, the scattering length for s-wave and scattering volume for p-wave case. However, the higher order terms, like the effective range, are needed in some circumstances. In this talk we discuss how the effective range alters the bulk and shear viscosity in both s- and p-wave Fermi gases in three dimensions, and whether the effective range is relevant in describing the dynamics. |
Wednesday, June 2, 2021 11:42AM - 11:54AM Live |
K07.00007: Interaction-assisted reversal of thermopower with ultracold atoms Jeffrey Mohan, Samuel Hausler, Philipp Fabritius, Laura Corman, Martin Lebrat, Tilman Esslinger We study thermoelectric currents of neutral, fermionic atoms flowing through a mesoscopic channel connecting a hot and a cold reservoir across the superfluid transition. The thermoelectric response results from a competition between density-driven diffusion from the cold to the hot reservoir and the channel which favors transport of energetic particles from hot to cold. We control the relative strength of both contributions to the thermoelectric response using an external optical potential in a nearly non-interacting and a strongly-interacting system. Without interactions, the magnitude of the particle current can be tuned over a broad range but is restricted to flow from hot to cold in our parameter regime. Strikingly, strong interparticle interactions reverse the direction of the current. We quantitatively model ab initio the non-interacting observations and qualitatively explain the interaction-assisted reversal by the reduction of entropy transport due to pairing correlations. |
Wednesday, June 2, 2021 11:54AM - 12:06PM Live |
K07.00008: Collisionless Damping in Co-propagaging Light and Atomic Beams with Optomechanical and Electronic Feedback Christopher Limbach The transverse stability of co-propagating light and matter beams is investigated in the collisionless regime, focusing on the interaction of optomechanical coupling and the electronic Kerr nonlinearity. The dynamic response of a classical monochromatic laser field and a mono-energetic beam of two-level atoms is studied through a Landau stability analysis of the Boltzmann and paraxial wave equations coupled by the gradient force and refractive index. The resulting dispersion relation captures both kinetic and saturation effects and shows that for blue detuning the homogeneous solution is unstable below a critical wavenumber which reduces to the Bespalov-Talanov instability in the limit of negligible optomechanical coupling. For red detuning, there exists a saturation threshold above which the kinetic instability stabilizes unconditionally. Even when saturation is negligible, an optomechanical analog of Landau damping stabilizes all wavenumbers above a critical wavenumber determined by the combined strength of the kinetic and refractive feedback. Numerical solution of the velocity-space perturbation reveals that the collisionless damping mechanism is related to the resonant interaction of atoms traveling along diagonals of the Talbot carpet. |
Wednesday, June 2, 2021 12:06PM - 12:18PM Live |
K07.00009: Third-quantization based method for studying quantum transport of interacting bosons Palak Dugar, Chih-Chun Chien Due to the Bose-Einstein statistics, the Fock space of a single site bosonic system can be infinite dimensional. For open quantum systems, the Lindblad master equation provides a reasonable description. When the Hamiltonian is quadratic, a method known as third quantization can be used to find the steady state. For interacting bosons, we apply the Hartree approximation to the third quantization method and to study the steady state density profiles and particle current. Compared to other numerical methods that truncate the local Fock space, the Hartree-third quantization method keeps the full Fock space but treats the interaction at the mean field level. To illustrate the power of this method, we demonstrate interaction based rectification and geometry based internal circulation of currents. Our method is suitable for studying quantum transport of ultracold atoms in engineered potentials. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700