Quantum walks of correlated photons in non-Hermitian photonic lattices

TL;DR

This paper demonstrates the experimental realization of two-photon quantum walks in non-Hermitian photonic lattices, revealing unidirectional behavior and entanglement suppression due to the skin effect, advancing understanding of open quantum systems.

Contribution

It introduces the first experimental study of two-photon quantum walks in non-Hermitian systems, highlighting entanglement suppression and unidirectional dynamics.

Findings

Observation of unidirectional quantum walks induced by the skin effect

Experimental evidence of entanglement suppression in non-Hermitian lattices

Insights into entanglement behavior in open quantum many-body systems

Abstract

Entanglement entropy characterizes the correlation of multi-particles and unveils the crucial features of open quantum systems. However, the experimental realization of exploring entanglement in non-Hermitian systems remains a challenge. In parallel, quantum walks have offered the possibility of studying the underlying mechanisms of non-Hermitian physics, which includes exceptional points, the non-Hermitian skin effect, and non-Bloch phase transitions. Unfortunately, these studies have only involved and prevailingly focused on the behavior of a single particle. Here, we propose and experimentally realize quantum walks of two indistinguishable photons in engineered non-Hermitian photonic lattices. We have successfully observed the unidirectional behavior of quantum walks in the bulk far from the edges induced by the skin effect. Moreover, we experimentally reveal the suppression of entanglement that is caused by the skin effect in non-Hermitian systems. Our study may facilitate a deep understanding of entanglement in open quantum many-body systems that are far from thermal equilibrium.