Spectral design principles for local-excitation retention in impurity-assisted atomic arrays

TL;DR

This paper develops spectral design principles for impurity-assisted atomic arrays to enhance local-excitation retention, using eigenmode analysis and inverse design to optimize configurations for prolonged excited states.

Contribution

It introduces a spectral surrogate objective for optimizing atomic array configurations to maximize local-excitation retention, demonstrating inverse design with nontrivial arrangements.

Findings

Eigenmode analysis reveals survival dynamics depend on decay rates and overlaps.

Spectral surrogate effectively guides the inverse design of atomic arrays.

Optimized configurations show enhanced local-excitation retention with aperiodic arrangements.

Abstract

Enhanced local-excitation retention in atomic arrays allows to exploit cooperative radiative effects to suppress emission and prolong excited-state lifetimes. We consider an impurity-assisted setting involving a single storage atom being initially excited and study the survival of local excitation under neither write nor retrieval fields. Because the corresponding dynamics can involve multiple interfering collective modes, the survival dynamics cannot determined from the smallest collective decay rate alone. Thus, using a biorthogonal eigenmode decomposition of an effective non-Hermitian Hamiltonian, we show that the survival dynamics are jointly governed by the decay rates of the eigenmodes and their overlaps with the initial excitation. Large oscillations occur when multiple long-lived modes have comparable weights. Accordingly, we introduce a physically motivated spectral surrogate objective that favors both small weighted decay rates and an initial-state weight concentrated on a single subradiant mode. As a proof of principle of this spectral design, we apply the surrogate to constrained atom-position optimization under minimum-distance constraints and obtain nontrivial aperiodic configurations with enhanced local-excitation retention. Our findings unveil spectral design principles for local-excitation retention in impurity-assisted atomic arrays and provide a proof of principle for their inverse design.