Interaction-induced non-Hermitian topological phases from a dynamical gauge field

TL;DR

This paper introduces a minimal non-Hermitian model where interactions induce topologically nontrivial complex energy spectra, revealing new phases in many-particle systems with potential realizations in atomic and optical setups.

Contribution

The work demonstrates how interactions can induce non-Hermitian topological phases in a dynamical gauge field model, extending topological concepts beyond single-particle systems.

Findings

Non-Hermitian topology emerges with multiple particles but not for single particles.

Effective doublon model accurately describes the nontrivial topology.

Proposes a Floquet protocol for experimental realization in atomic and optical systems.

Abstract

We present a minimal non-Hermitian model where a topologically nontrivial complex energy spectrum is induced by inter-particle interactions. Our model consists of a one-dimensional chain with a dynamical non-Hermitian gauge field with density dependence. The model is topologically trivial for a single particle system, but exhibits nontrivial non-Hermitian topology with a point gap when two or more particles are present in the system. We construct an effective doublon model to describe the nontrivial topology in the presence of two particles, which quantitatively agrees with the full interacting model. Our model can be realized by modulating hoppings of the Hatano-Nelson model; we provide a concrete Floquet protocol to realize the model in atomic and optical settings.