Topological Origin of Non-Hermitian Skin Effects

TL;DR

This paper uncovers that the non-Hermitian skin effect stems from intrinsic topology, revealing new symmetry-protected skin effects and expanding understanding of bulk-boundary correspondence in non-Hermitian systems.

Contribution

It demonstrates the topological origin of the skin effect, introduces symmetry-protected skin effects, and classifies possible skin effects across dimensions.

Findings

Discovery of $ ext{Z}_2$ skin effect protected by time-reversal symmetry

Unified topological explanation for the skin effect

Discussion of skin effects in arbitrary dimensions

Abstract

A unique feature of non-Hermitian systems is the skin effect, which is the extreme sensitivity to the boundary conditions. Here, we reveal that the skin effect originates from intrinsic non-Hermitian topology. Such a topological origin not merely explains the universal feature of the known skin effect, but also leads to new types of the skin effects---symmetry-protected skin effects. In particular, we discover the $\mathbb{Z}_{2}$ skin effect protected by time-reversal symmetry. On the basis of topological classification, we also discuss possible other skin effects in arbitrary dimensions. Our work provides a unified understanding about the bulk-boundary correspondence and the skin effects in non-Hermitian systems.