Quantum correlations of localized atomic excitations in a disordered atomic chain

Abstract

The atom-waveguide interface mediates significant and long-range light-matter interactions through guided modes. In this one-dimensional system, we theoretically investigate the excitation localization of multiple atomic excitations under strong position disorder. 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 those without disorder. This indicates two distinct regimes in time: before the onset of excitation localization, the disorder engage the disturbance of quantum correlations, which is followed by disorder-assisted buildup 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 disorder 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 into the studies of few-body localization phenomenon and nonequilibrium dynamics in open quantum systems.