Quantum correlations of localized atomic excitations in a disordered atomic chain

TL;DR

This paper investigates how strong position disorder affects quantum correlations and localization of multiple atomic excitations in a one-dimensional atom-waveguide system, revealing distinct temporal regimes and the influence of coupling directionality.

Contribution

It provides a theoretical analysis of excitation localization and quantum correlation dynamics under disorder, highlighting the roles of disorder strength, range, and coupling directionality in a 1D atomic chain.

Findings

Quantum correlations initially decrease then stabilize due to disorder.

Longer-range correlations take more time to be affected by disorder.

Directional couplings can transition the system toward delocalization.

Abstract

Atom-waveguide interface mediates significant and long-range light-matter interactions through the guided modes. In this one-dimensional system, we theoretically investigate the excitation localization of multiple atomic excitations under strong position disorders. Deep in the localization side, we obtain the time evolutions of quantum correlations via Kubo cumulant expansions, which arise initially and become finite and leveled afterward, overtaking the ones without disorders. This indicates two distinct regimes in time: before the onset of excitation localization, the disorders engage the disturbance of quantum correlations, which is followed by disorder-assisted build-up of quantum correlations that maintain at a later stage owing to the absence of excitations diffusion. The crossing of distinct regimes is pushed further in time for longer-range correlations, which indicates a characteristic timescale needed for disorders to sustain them. We also explore the effect of directionality of couplings and resonant dipole-dipole interactions, which can drive the system toward the delocalized side when it is under chiral couplings or large dipole-dipole interaction strengths. The time-evolved quantum correlations can give insights to the studies of few-body localization phenomenon and nonequilibrium dynamics in open quantum systems.