Observation of non-Hermitian topological Anderson insulator in quantum dynamics

TL;DR

This paper experimentally demonstrates a non-Hermitian topological Anderson insulator using disordered photonic quantum walks, revealing complex localization phenomena and topological phase transitions in open quantum systems.

Contribution

It provides the first experimental simulation and characterization of the non-Hermitian topological Anderson insulator in a photonic system, exploring localization and topological transitions.

Findings

Observation of non-monotonous Lyapunov exponent behavior

Detection of disorder-induced topological phase transitions

Evidence of biorthogonal criticality in topological phases

Abstract

Disorder and non-Hermiticity dramatically impact the topological and localization properties of a quantum system, giving rise to intriguing quantum states of matter. The rich interplay of disorder, non-Hermiticity, and topology is epitomized by the recently proposed non-Hermitian topological Anderson insulator that hosts a plethora of exotic phenomena. Here we experimentally simulate the non-Hermitian topological Anderson insulator using disordered photonic quantum walks, and characterize its localization and topological properties. In particular, we focus on the competition between Anderson localization induced by random disorder, and the non-Hermitian skin effect under which all eigenstates are squeezed toward the boundary. The two distinct localization mechanisms prompt a non-monotonous change in profile of the Lyapunov exponent, which we experimentally reveal through dynamic observables. We then probe the disorder-induced topological phase transitions, and demonstrate their biorthogonal criticality. Our experiment further advances the frontier of synthetic topology in open systems.