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O: Fachverband Oberflächenphysik

O 122: Topology and Symmetry Protected Materials II

O 122.2: Vortrag

Freitag, 20. März 2020, 10:45–11:00, WIL A317

Topological transport quantization by dissipation in fast Thouless pumps — •Zlata Fedorova, Haixin Qiu, Stefan Linden, and Johann Kroha — Physikalisches Institut, Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 12, 53115 Bonn, Germany.

Quantized particle pumping in a slowly varying one-dimensional potential has played a prominent role in the development of topology as a concept in condensed matter physics. In the adiabatic regime, the net particle transfer per pumping cycle is an integer given by the Chern number, i.e., a topological invariant, and therefore is robust against topology-preserving perturbations. However, at finite driving frequencies the system becomes topologically trivial due to the coupling between forward- and backward-propagating states. As a result, the particle transport deviates from perfect quantization, which poses a problem for the experimental observation of Thouless pumping. Here, on the example of the driven Rice-Mele model we introduce time-periodic modulation of dissipation as a new concept to overcome this problem. The basic idea is to selectively suppress transport in one direction, while allowing it in another by making use of the distinct spatial and temporal amplitude distributions of the eigenstates moving in the corresponding directions. Restoration of quantized pumping under such periodic losses is confirmed by the Floquet analysis and by the experiments based on plasmonic waveguide arrays.