Freiburg 2019 – wissenschaftliches Programm
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FM: Fall Meeting
FM 10: Topology: Artificial Systems
FM 10.5: Talk
Montag, 23. September 2019, 15:15–15:30, 1199
Creating anomalous Floquet Chern insulators with magnetic quantum walks — M. Sajid1, J. K. Asbóth2, D. Meschede1, R. F. Werner3, and •A. Alberti1 — 1Institut für Angewandte Physik, Universität Bonn, Germany — 2Wigner Research Centre for Physics, Budapest, Hungary — 3Institut für Theoretische Physik, Leibniz Universität Hannover, Germany
We propose a realistic scheme to construct anomalous Floquet Chern topological insulators using spin-1/2 particles carrying out a discrete-time quantum walk in a two-dimensional lattice [1]. By Floquet engineering the quantum-walk protocol, an Aharonov-Bohm geometric phase is imprinted onto closed-loop paths in the lattice, thus realizing an Abelian gauge field, the analog of a magnetic flux threading a two-dimensional electron gas. We find that because of the nonperturbative nature of the periodic driving, a second topological number in addition to Chern number is necessary to fully characterize the anomalous Floquet topological phases of magnetic quantum walks and to compute the number of topologically protected edge modes expected at the boundaries between different phases. We discuss an implementation of this scheme using neutral atoms in two-dimensional spin-dependent optical lattices, which enables the generation of arbitrary magnetic-field landscapes, including those with sharp boundaries. Magnetic quantum walks may open a new route to studying topological properties of charged particles in strong magnetic fields.
[1] M. Sajid et al., Phys. Rev. B (in press, 2019)