Bulletin of the American Physical Society
50th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics APS Meeting
Volume 64, Number 4
Monday–Friday, May 27–31, 2019; Milwaukee, Wisconsin
Session N05: Dynamics of Cold Atoms in Optical Lattices 
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Chair: Bryce Gadway, University of Illinois UrbanaChampaign Room: Wisconsin Center 102C 
Thursday, May 30, 2019 8:00AM  8:12AM 
N05.00001: Optical Lattice with Torus Topology Hwanmun Kim, Guanyu Zhu, J. V. Porto, Mohammad Hafezi We propose an experimental scheme to construct an optical lattice where the atoms are confined to the surface of a torus. This construction can be realized with spatially shaped laser beams which could be realized with recently developed high resolution imaging techniques. We numerically study the feasibility of this proposal by calculating the tunneling strengths for atoms in the torus lattice. To illustrate the nontrivial role of topology in atomic dynamics on the torus, we study the quantized superfluid currents and fractional quantum Hall (FQH) states on such a structure. For FQH states, we numerically investigate the robustness of the topological degeneracy and propose an experimental way to detect such a degeneracy. Our scheme for torus construction can be generalized to surfaces with higher genus for exploration of richer topological physics. [Preview Abstract] 
Thursday, May 30, 2019 8:12AM  8:24AM 
N05.00002: Optical lattices with periodicity well below $\lambda $/2 Sarthak Subhankar, Yang Wang, TszChun Tsui, James V. Porto, Steven Rolston Optical potentials based on the acStark shift are used extensively in the investigation of lattice models of quantum many body systems. But these potentials are limited by diffraction to have a lattice constant no less than $\lambda/2$, where $\lambda$ is the wavelength of light used. This sets a temperature scale in these lattices given by $T\sim E_R/k_B$ , where $E_R=h^2/(8md^2)$ and $d$ is the lattice constant. Study of phenomena like superexchange and magnetic dipole interactions require much lower temperatures than that set by $E_R$. By engineering lattices with subwavelength lattice constants, the temperature requirements to study these phenomena can be relaxed. Recently, we have demonstrated an optical lattice based on dark states with subwavelength barriers of width $\lambda/50$ [1]. By stroboscopically dithering the phase of this lattice while remaining in a dark state, a timeaveraged potential with subwavelength lattice spacing of $\lambda/(2N)$ can be realized [2]. Here we report our progress on the realization of such a lattice. [1] Phys. Rev. Lett. 120, 083601 [2] Phys. Rev. Lett. 115, 140401 [Preview Abstract] 
Thursday, May 30, 2019 8:24AM  8:36AM 
N05.00003: Quantum optomechanics of a twodimensional atomic array Ephraim Shahmoon, Mikhail Lukin, Susanne Yelin We demonstrate that a twodimensional (2D) atomic array can be used as a novel platform for quantum optomechanics. Such arrays feature both nearlyperfect reflectivity and ultralight mass, leading to significantlyenhanced optomechanical phenomena. Considering the collective atomarray motion under continuous laser illumination, we study the nonlinear optical response of the array. We find that the spectrum of light scattered by the array develops multiple sidebands, corresponding to collective mechanical resonances, and exhibits nearly perfect quantumnoise squeezing. Possible extensions and applications for quantum nonlinear optomechanics are discussed. [Preview Abstract] 
Thursday, May 30, 2019 8:36AM  8:48AM 
N05.00004: Siteselective loading of atoms into a lattice for homogeneous coupling between atoms and probe light Baochen Wu, Graham P. Greve, Chengyi Luo, James K. Thompson Many AMO experiments utilize atoms trapped along a 1D optical lattice. The atoms are manipulated or interrogated with a standing wave probing laser wavelength incommensurate with the lattice, and the positions of the atoms along the lattice axis lead to inhomogeneous coupling between the atoms and the probing light. As a result, optomechanical issues arise, coherent interactions are degraded, and the underlying physics may be obscured. We explore a new scheme for homogeneous coupling involving a ``microwaveknife'' that allows blowing away atoms at lattice sites that are not maximallycoupled to the probing laser. As such, it may be appropriate in situations where other techniques, e.g. a commensurate lattice, a ring cavity, or timeaveraged probing measurements, are not feasible. [Preview Abstract] 
Thursday, May 30, 2019 8:48AM  9:00AM 
N05.00005: Quantum walk of ultracold atoms in optical lattices with quadratic gradients Lushuai Cao, QianRu Zhu, XiaoChun Duan, YaoYao Xu Quantum walk of ultracold atoms in optical lattices has become a powerful platform for various applications, such as in quantum metrology and quantum simulation. A paradigmatic example is the Bloch oscillations in optical lattices with a linear gradient, which has been used to measure the gravity acceleration. In this talk, I will present our numerical results on quantum walk of ultracold atoms in optical lattices with a linear plus quadratic gradient. A modulated Bloch oscillation is observed, of which the frequency spectrum of the local density oscillations present equidistant splitting. Such frequency splitting has a potential use in measure, $e.g.$ the gravity gradients. [Preview Abstract] 
Thursday, May 30, 2019 9:00AM  9:12AM 
N05.00006: Fast eigenstate preparation in a synthetic lattice by counterdiabatic driving Eric Meier, Kinfung Ngan, Fangzhao Alex An, Dries Sels, Bryce Gadway In many experimental systems, the adiabatic theorem of quantum mechanics is used to prepare eigenstates through slow continuous changes to the Hamiltonian. Altering a Hamiltonian diabatically however, can result in coupling of the eigenstates. In some systems these diabatic terms can be calculated and exactly cancelled through the addition of counterdiabatic terms to the Hamiltonian. By applying these counterdiabatic techniques, a Hamiltonian can be changed faster than adiabatically possible with little to no coupling between eigenstates. We present the realization of this technique in a multistate, tightbinding synthetic lattice system formed by momentum states of rubidium atoms, where complete local and timedependent control over the Hamiltonian allows for the addition of these counterdiabatic terms. As an example of this technique, we show the fast preparation of the eigenstates of a fewsite lattice with open boundaries, as well as the transport of all population from the leftmost site to the rightmost site of a synthetic lattice with $\sim$10 sites. This technique allows for rapid eigenstate preparation and readout, making it useful for studying critical eigenstates of topological and disordered tightbinding models, and potentially for matterwave interferometry. [Preview Abstract] 
Thursday, May 30, 2019 9:12AM  9:24AM 
N05.00007: Resonant leapfrog dynamics of interacting spinorbit coupled fermions in optical lattices Mikhail Mamaev, Ana Maria Rey Ultracold atoms in optical lattices offer a powerful platform for studying interplay between singleparticle motion and interactions. We investigate the manybody dynamics of strongly interacting spin1/2 fermions under a laser drive that induces spinorbit coupling. The drive frequency is made resonant with the Hubbard repulsion, inducing nonperturbative densitydependent tunneling. An isolated atom is confined, but two or more neighbours enable motion for each other. This setup yields resonanceassisted interacting dynamics on fast timescales in the Mott insulating limit, as an alternative to prior experiments using tilted lattices. The system exhibits paritydependent longtime localization of initial atomic configurations, where odd strings of atoms become stuck while even ones spread ballistically. In addition, longrange doublon correlations are developed at higher filling fraction. All results are accessible with current stateoftheart experiments using alkaline earth atoms. [Preview Abstract] 
Thursday, May 30, 2019 9:24AM  9:36AM 
N05.00008: Spin Transport in a Mott Insulator of Ultracold Fermions Matthew Nichols, Lawrence Cheuk, Melih Okan, Thomas Hartke, Enrique Mendez, Senthil Todadri, Ehsan Khatami, Hao Zhang, Martin Zwierlein Strongly correlated materials such as the high$T_{c} $superconducting cuprates are expected to feature unconventional transport properties, where charge, spin, and heat conduction are decoupled. However, the measurement of spin transport in such materials is  in contrast to charge transport  highly challenging. In this talk, we report on a study of spin transport in the twodimensional FermiHubbard model using a quantum gas microscope of ultracold $^{\mathrm{40}}$K atoms trapped in a square optical lattice. By applying a spindependent potential gradient to a homogeneous, Mottinsulating sample at halffilling, we are able to observe, in real time, how the spin dynamics evolve in linear response. By varying the relative strength of the onsite interactions, we find that spin transport is driven by superexchange and doublonholeassisted tunneling in the strongly interacting regime. For a wide range of experimental parameters, the spin dynamics are found to be diffusive in nature, and we extract both the spin diffusion coefficient and the spin conductivity. Because theoretical calculations of these transport coefficients are notoriously difficult due to strong correlations present in the system, these measurements present a valuable benchmark for future theoretical developments. [Preview Abstract] 
Thursday, May 30, 2019 9:36AM  9:48AM 
N05.00009: Coherent optical transients with quantized atomic motion Huy Nguyen, Alex Kuzmich, Paul Berman We consider coherent transients in which a sequence of optical pulses is incident on a sample of trapped atoms and gives rise to phasematched emission. The trapping potential for the atoms can be statedependent, necessitating a quantum treatment of the centerofmass motion. We follow a sourcefield approach, modified to account for the quantized motion of the atoms. A specific example involving the creation of groundRydberg level coherence in an optical lattice is analyzed. Accounting for the statedependent optical potentials for the hyperfine levels in the Rydberg manifold, we find good agreement between theory and experiment. [Preview Abstract] 

N05.00010: ABSTRACT WITHDRAWN 
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