SKM 2023 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 17: Topology: Quantum Hall Systems
TT 17.6: Vortrag
Montag, 27. März 2023, 18:15–18:30, HSZ 304
Observation and applications of non-Hermitian topology in a multi-terminal quantum Hall device — •Kyrylo Ochkan1, Viktor Könye1, Anastasiia Chyzhykova1,2, Jan Budich3, Jeroen van den Brink1, Cosma Fulga1, and Joseph Kyrylo1 — 1IFW Dresden, Deutschland — 2Taras Shevchenko National University of Kyiv, Ukraine — 3TU Dresden, Deutschland
One of the simplest examples of non-Hermitian topology is encountered in the Hatano-Nelson (HN) model, a one-dimensional chain where the hopping in one direction is larger than in the opposite direction. We present here the first experimental observation of non-Hermitian topology in a quantum condensed-matter system. The measurements are done in a multi-terminal quantum Hall device etched in a high mobility GaAs/AlGaAs two-dimensional electron gas ring. The conductance matrix that connects the currents flowing from the active contacts to the ground with the voltage of the active contacts is topologically equivalent to the HN Hamiltonian.
In our device, we directly measure and evidence the non-Hermitian skin effect. We also compute for our experimental device two topological invariants that are found to be more robust than the Chern number. We finally use the unique properties of our system and continuously tune the system configuration between open and periodic boundary conditions.
In this talk, we present the latest developments with regard to the application of the devices with these topological properties.