Many-body topology of non-Hermitian systems

TL;DR

This paper demonstrates that intrinsic non-Hermitian topological phases in one-dimensional systems persist even with many-body interactions, introducing a many-body topological invariant and exploring the interacting Hatano-Nelson model.

Contribution

It introduces a many-body topological invariant for non-Hermitian systems and shows the survival of topological phases with interactions, expanding understanding beyond noninteracting models.

Findings

Intrinsic non-Hermitian topological phases survive many-body interactions

A many-body topological invariant based on the spectrum winding is formulated

Interacting Hatano-Nelson model exhibits a unique topological phase and skin effect

Abstract

Non-Hermiticity gives rise to unique topological phases that have no counterparts in Hermitian systems. Such intrinsic non-Hermitian topological phases appear even in one dimension while no topological phases appear in one-dimensional Hermitian systems. Despite the recent considerable interest, the intrinsic non-Hermitian topological phases have been mainly investigated in noninteracting systems described by band theory. It has been unclear whether they survive or reduce in the presence of many-body interactions. Here, we demonstrate that the intrinsic non-Hermitian topological phases in one dimension survive even in the presence of many-body interactions. We formulate a many-body topological invariant by the winding of the complex-valued many-body spectrum in terms of a U (1) gauge field (magnetic flux). As an illustrative example, we investigate the interacting Hatano-Nelson model and find a unique topological phase and skin effect induced by many-body interactions.