Regensburg 2022 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 11: Topology: Quantum Hall Systems
TT 11.8: Vortrag
Dienstag, 6. September 2022, 11:30–11:45, H10
Non-Hermitian topological signatures in a quantum Hall system — •Raghav Chaturvedi1, Kyrylo Ochkan1, Viktor Könye1, Ewelina Hankiewicz2, Jeroen van den Brink1, Joseph Dufouleur1, and Cosma Fulga1 — 1IFW Dresden, Deutschland — 2Julius Maximilian University of Würzburg
Reflection matrices describing waves reflected from the boundaries of insulators exhibit non-Hermitian topological signatures. Drawing from this, we propose to realize non-Hermitian topology in the quantum regime of a two dimensional condensed-matter system. Our work is based on the insight that, in the limit of maximal non-reciprocity, the Hamiltonian for the simplest topological non-Hermitian system -- the Hatano-Nelson chain -- effectively describes a one-dimensional, unidirectionally propagating mode. This is analogous to the unidirectional boundary mode of a fully Hermitian topological insulator: the quantum Hall system. We show that the multi-terminal conductance matrix of this system exhibits a topologically protected non-Hermitian skin effect. Moreover, we show that the topological invariant characterizing these features is more robust than the Chern number, as it remains well-quantized even across quantum Hall plateau transitions. Our work shows that the transport properties of Chern insulators may exhibit signatures of non-Hermitian topology, and this paves the way for the first experimental observation of non-Hermitian topology in a quantum condensed-matter system, which will be presented by another author.