Observing edge dynamics in topological Floquet systems

Floquet engineering, i.e., periodic modulation of a system’s parameters, has proven as a powerful experimental tool for the realization of quantum systems with exotic properties that have no static analog. In particular, the so-called anomalous Floquet phase displays topological properties even if the Chern number of the bulk band vanishes [1]

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Our experimental system consists of bosonic atoms in a periodically driven honeycomb lattice.

Depending on the driving parameters several out-of-equilibrium topological phases can be realized,

including an anomalous phase [2]. Recently, we have added programmable optical potentials to study

the edge dynamics in such topological systems. We are investigating the real-space evolution of an initially

localized wavepacket close to the edge after releasing it from a tightly-focused optical tweezer. We observe the chiral

nature of the edge state, even in the anomalous Floquet phase, thereby directly revealing the topological nature of this phase.

[1] Rudner, et al. Anomalous edge states and the bulk-edge correspondence for periodically-driven two dimensional systems, Phys. Rev. X 3, 031005 (2013)

[2] Wintersperger, et al. Realization of an anomalous Floquet topological system with ultracold atoms. Nat. Phys. 16, 1058–1063 (2020)