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 K06: Ultracold Atoms in Driven Optical Lattices |
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Chair: Logan Clark, University of Chicago Room: Wisconsin Center 102DE |
Wednesday, May 29, 2019 2:00PM - 2:30PM |
K06.00001: Synthetic gauge fields with ultracold atoms in periodically-driven lattices Invited Speaker: Monika Aidelsburger Ultracold atoms in optical lattices are powerful experimental platforms to study a variety of phenomena ranging from condensed-matter to statistical physics. Recently, a promising new direction was opened by the successful realization of paradigmatic topological condensed matter models, in particular the Hofstadter and the Haldane model. Topological states of matter exhibit unique conductivity properties, which are particularly robust against perturbations. One of the most prominent examples are quantum Hall insulators. I will introduce some of the most common methods used to generate topological band structures in ultracold atoms based on Floquet engineering. This method relies on periodic modulation of the systems’ parameters to emulate the properties of an otherwise inaccessible static system. The successful implementation of these techniques led to the direct observation of bulk topological properties and chiral currents in optical lattices with synthetic gauge fields. Floquet engineering can further been employed to simulate density-dependent gauge fields or even complete gauge theories, which require an interaction between matter and gauge fields. One example is the realization of $\mathbb{Z}_2$ lattice gauge theories, which play an important role in condensed matter physics and quantum computation. Recently, we have implemented such a model with a two-component mixture of ultracold bosons in a double-well potential $-$ the basic building block of $\mathbb{Z}_2$ lattice gauge theories. The rich properties of Floquet systems, however, go well beyond those of their static counterparts. The quasienergy spectrum can have a non-trivial winding number, which leads to the appearance of anomalous chiral edge modes in the quasienergy spectrum. For instance, an anomalous Floquet insulator with topologically trivial bulk bands can present topologically protected chiral edge modes. These intriguing phases can be directly observed, e.g., in periodically driven honeycomb lattices. [Preview Abstract] |
Wednesday, May 29, 2019 2:30PM - 3:00PM |
K06.00002: New approaches to topological phases with ultracold atoms Invited Speaker: Christof Weitenberg Ultracold atoms in optical lattices constitute a versatile platform to study the fascinating phenomena of gauge fields and topological matter. Periodic driving can induce topological band structures with non-trivial Chern number of the effective Floquet Hamiltonian and paradigmatic models, such as the Haldane model on the honeycomb latticce, can be directly engineered. In this talk, I will report on recent experiments, in which we realized new approaches for measuring the Chern number in this system. This includes the observation of quantized circular dichroism, which is revealed in chiral spectroscopy between the Floquet bands. Furthermore, we study the dynamics of the system after a quench into the topological regime using time-resolved Bloch-state tomography and obtain the Chern number from topological properties of the emerging dynamical vortices. We also apply state-of-the-art deep learning techniques to our momentum-space images and train a network to recognize the Chern number from single images, which allows mapping out the full two-dimensional Haldane phase diagram. These new approaches to topology also define a promising starting point for probing topological order of interacting systems such as fractional Chern insulators. [Preview Abstract] |
Wednesday, May 29, 2019 3:00PM - 3:30PM |
K06.00003: Lattice-trapped lithium as tunable Floquet matter Invited Speaker: David Weld Degenerate lithium in modulated optical lattices makes a near-ideal testbed for the experimental study of quantum matter driven far from equilibrium. We will present a sequence of recent experimental results: flexible Floquet engineering of band structure and transport properties, direct imaging of Floquet-Bloch bands using position-space Bloch oscillations, detailed experimental mapping of the properties of prethermal Floquet matter, and an observation of anomalously slow heating in a rapidly driven interacting gas. [Preview Abstract] |
Wednesday, May 29, 2019 3:30PM - 4:00PM |
K06.00004: Engineering synthetic lattices with driven optical lattices Invited Speaker: Bryce Gadway The concept of synthetic dimensions or synthetic lattices - where a set of internal or external states of a particle can be resonantly coupled together to form the sites of an effective tight-binding model - has enabled the recent development of new capabilities in the engineering of novel Hamiltonians in atomic, molecular, and optical systems. We describe how a set of linear momentum states of atomic matter waves can be resonantly coupled together by Bragg laser fields to form large, tunable synthetic lattices. Such simultaneous driving by multiple Bragg laser fields can alternatively be described as a temporal variation of the phase and amplitude of a periodic lattice potential. We describe how this method of lattice driving can allow for the spectroscopic engineering of effective tight-binding models with tunable disorder and topology, and how native atomic interactions in this system can give rise to correlated synthetic lattice dynamics. Finally, we discuss future prospects and generalizations of these techniques. [Preview Abstract] |
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