Exceptional Non-Hermitian Phases in Disordered Quantum Wires

TL;DR

This paper uncovers non-Hermitian topological phases with exceptional points in disordered quantum wires, highlighting the role of disorder-induced self-energy and providing experimental signatures and numerical validation.

Contribution

It introduces a minimal framework for realizing and studying topological non-Hermitian phases in disordered quantum systems, emphasizing the necessity of multiple nodal points for stabilization.

Findings

Exceptional non-Hermitian phases with exceptional degeneracies are found in disordered quantum wires.

Disorder can stabilize non-Hermitian exceptional points when at least two nodal points exist.

Experimental signatures are identified in spectral functions and quantum transport properties.

Abstract

We demonstrate the occurrence of nodal non-Hermitian (NH) phases featuring exceptional degeneracies in chiral-symmetric disordered quantum wires, where NH physics naturally arises from the self-energy in a disorder-averaged Green's function description. Notably, we find that at least two nodal points in the clean Hermitian system are required for exceptional points to be effectively stabilized upon adding disorder. We identify and study experimental signatures of our theoretical findings both in the spectral functions and in mesoscopic quantum transport properties of the considered systems. Our results are quantitatively corroborated and exemplified by numerically exact simulations on a microscopic lattice model. The proposed setting provides a conceptually minimal framework for the realization and study of topological NH phases in quantum many-body systems.