Magnetic suppression of non-Hermitian skin effects

TL;DR

This paper demonstrates that applying a magnetic field can significantly suppress the non-Hermitian skin effect by restoring the validity of low-energy descriptions, thus reducing the accumulation of bulk states at system boundaries.

Contribution

It introduces the concept that magnetic fields can control and suppress the non-Hermitian skin effect, challenging previous understanding of its topological origin.

Findings

Magnetic fields push skin states back into the bulk

The skin topological area is sharply reduced by magnetic flux

Generalized Brillouin zone becomes irrelevant with rational gauge fluxes

Abstract

Skin effect, where macroscopically many bulk states are aggregated towards the system boundary, is one of the most important and distinguishing phenomena in non-Hermitian quantum systems. We discuss a new aspect of this effect whereby, despite its topological origin, applying magnetic field can largely suppress it. Skin states are pushed back into the bulk and the skin topological area, which we define, is sharply reduced. As seen from exact solutions of representative models this is fundamentally rooted in the fact that the applied magnetic field restores the validity of the low-energy description that is rendered inapplicable in the presence of non-Bloch skin states. We further study this phenomenon using rational gauge fluxes, which reveals a unique irrelevance of the generalized Brillouin zone in the standard non-Bloch band theory of non-Hermitian systems.