Dresden 2026 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 83: Topology: Quantum Hall Systems
TT 83.3: Talk
Thursday, March 12, 2026, 15:30–15:45, HSZ/0105
Non-Hermitian topology of transport in the quantum Hall phases in graphene — •Raghav Chaturvedi1,2, Ewelina M. Hankiewicz2, Jeroen van den Brink1, and Ion Cosma Fulga1 — 1Leibniz Institute for Solid State and Materials Research, IFW Dresden, Germany — 2Institute for Theoretical Physics and Astrophysics, Julius-Maximilians-Universität Würzburg, Germany
Signatures of non-Hermitian topology can be realized in a conventional quantum Hall device connected to multiple current sources. These signatures manifest as robust current-voltage characteristics, dictated by the presence of a nontrivial, non-Hermitian topological invariant of the conductance matrix. Chiral edge states are believed to be responsible for this non-Hermitian response, similar to how they lead to a quantized Hall conductivity in the presence of a single current source. Here, we go beyond this paradigm, showing that multiterminal conductance matrices can exhibit non-Hermitian topological phase transitions that cannot be traced back to the presence and directionality of a boundary-localized chiral mode. By performing quantum transport simulations in the quantum Hall regime of graphene, we find that when the chemical potential is swept across the zeroth Landau level, unavoidable device imperfections cause the appearance of an additional non-Hermitian phase of the conductance matrix. This highlights graphene as an ideal platform for the study of non-Hermitian topological phase transitions, and is a first step towards exploring how the geometry of quantum devices can be harnessed to produce robust, topologically-protected transport characteristics.
Keywords: Non-Hermitian; Topology; graphene; quantum hall; transport