Group Seminar via Zoom: Realization and characterization of an anomalous Floquet topological
system with ultracold atoms

Karen Wintersperger, LMU
Group meeting via video conference (Zoom)
Tuesday, July 21st, 09:00 (MEZ)

Dealing with the unique situation of partial lock downs worldwide and home office solutions at our Institute due to the current spreading of the Covid 19 virus, we are now holding our group seminars and journal clubs via video conference. This procedure enables us to continue our research, enhance discussions and exchange important information.

Abstract:

Ultracold atoms in periodically-driven optical lattices can be used to simulate systems with nontrivial topological properties. Due to the periodic driving, energy conservation is relaxed which makes it possible to realize systems with properties that go beyond those of conventional static systems. For instance, chiral edge modes can exists even if the bulk is topologically trivial [1].
We study such anomalous Floquet phases experimentally using a BEC of K39 in an optical honeycomb lattice with periodically modulated tunnel couplings. By monitoring the closing and reopening of energy gaps in the band structure we are able to track the transitions between different Floquet phases. Moreover, we probe the topological properties of the bulk by measuring the Hall deflection induced by local changes in the Berry curvature. Combining these measurements enables us to extract the topological invariants of the bulk bands and the energy gaps, which are both required to accurately classify the topological phases of Floquet systems [2, 3].

[1] T. Kitagawa et al., Phys. Rev. B 82, 235114 (2010)
[2] M. Rudner et al., PRX 3, 031005 (2013)
[3] N. Ünal et al., PRL 122, 253601 (2019)

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