Non-Hermitian topology of transport in the quantum Hall phases in graphene

Abstract

It has recently been shown that 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 multi-terminal 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 monolayer 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.

arXiv comment10 pages, 10 figures. Horizon European funding; Non-Hermitian topological systems and their applications for sensors, NHTS 101151049

References in corpus (24)

• Two-Dimensional Gas of Massless Dirac Fermions in Graphene
• Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator
• Random-Matrix Theory of Quantum Transport
• Edge states and topological invariants of non-Hermitian systems
• Exceptional Topology of Non-Hermitian Systems
• Non-Hermitian Physics
• Localization transitions in non-Hermitian quantum mechanics
• Kwant: a software package for quantum transport
• Observation of bulk boundary correspondence breakdown in topolectrical circuits
• Observation of non-Hermitian bulk-boundary correspondence in quantum dynamics
• Efficient Light Funneling based on the non-Hermitian Skin Effect
• Non-Hermitian robust edge states in one-dimension: Anomalous localization and eigenspace condensation at exceptional points
• Observation of non-Hermitian topology and its bulk-edge correspondence in an active mechanical metamaterial
• Non-reciprocal robotic metamaterials
• Non-Hermitian Topological Sensors
• Observation of Non-Hermitian Skin Effect and Topology in Ultracold Atoms
• Acoustic non-Hermitian skin effect from twisted winding topology
• Observation of higher-order non-Hermitian skin effect
• Topological Correspondence between Hermitian and Non-Hermitian Systems: Anomalous Dynamics
• Skin effect and winding number in disordered non-Hermitian systems
• K-Theory and Pseudospectra for Topological Insulators
• Observation of non-Hermitian topology in a multi-terminal quantum Hall device
• Amplification of quantum signals by the non-Hermitian skin effect
• Non-Hermitian topological ohmmeter