Concentrated subradiant modes in one-dimensional atomic array coupled with chiral waveguides

TL;DR

This paper investigates non-Hermitian physics in a chiral waveguide-coupled atomic array, revealing subradiant modes localized at the interface due to the non-Hermitian skin effect, with potential applications in quantum optics.

Contribution

It introduces a novel non-Hermitian atom-waveguide system demonstrating the non-Hermitian skin effect and subradiant mode localization in a one-dimensional atomic array.

Findings

Subradiant modes concentrate at the interface, indicating the skin effect.

Superradiant modes remain extended, showing different localization behaviors.

The subradiant funneling effect is robust against atomic disorder.

Abstract

Non-Hermitian systems have recently attracted broad interest and exhibited intriguing physical phenomena, in which the non-Hermitian skin effect is one of the most remarkable quantum phenomena desiring detailed investigations and has been widely studied in various fermionic and bosonic systems. Here we propose a non-Hermitian atom-waveguide system composed of a tilted one-dimensional atomic array coupled with two identical waveguides with opposite chiralities. Such system creates an effective lattice model including nonreciprocal long-range hoppings through the chiral-waveguide photon-mediated interactions. We find the excitation of the collective atomic states concentrates in the middle interface, pointing towards the non-Hermitian skin effect associated with subradiant modes, while, on the contrary, superradiant modes exhibit extended features. Simulation results present subradiant funneling effect, with robustness against small atomic position disorders. Our work underpins the fundamental comprehension towards the non-Hermitian skin effect in open quantum systems and also provide prospective paths to study non-Hermitian systems in the area of quantum optics.