The non-Hermitian skin effect: A perspective

TL;DR

This paper reviews the non-Hermitian skin effect, highlighting its topological nature, recent higher-dimensional and many-body studies, and discussing experimental signatures and potential applications.

Contribution

It provides a comprehensive perspective on the NH skin effect, emphasizing its topological origin, recent advances in higher dimensions and many-body systems, and experimental implications.

Findings

NH skin effect is a topological phenomenon with unique boundary state accumulation.

Recent studies extend understanding to higher dimensions and many-body systems.

Experimental signatures and applications are actively being explored.

Abstract

The non-Hermitian (NH) skin effect is a truly NH feature, which manifests itself as an accumulation of states, known as skin states, on the boundaries of a system. In this perspective, we discuss several aspects of the NH skin effect focusing on the most interesting facets of this phenomenon. Beyond reviewing necessary requirements to see the NH skin effect, we discuss the NH skin effect as a topological effect that can be seen as a manifestation of a truly NH bulk-boundary correspondence, stemming from the spectral topology, and show how skin states can be distinguished from topological boundary states. As most theoretical work has focused on studying the NH skin effect in one-dimensional non-interacting systems, recent developments of studying this effect in higher dimensions as well as in many-body systems are highlighted. Lastly, experimental signatures and applications are discussed, and an outlook is provided.