A subradiant optical mirror formed by a single structured atomic layer

TL;DR

This paper demonstrates that a single monolayer of atoms arranged in a 2D array can act as an efficient, tunable optical mirror through cooperative subradiant effects, advancing quantum light-matter interface engineering.

Contribution

It provides the first direct observation of a subradiant atomic array functioning as a mirror, with control over its optical properties via spatial order and atomic dynamics.

Findings

Array acts as an efficient mirror with spectral narrowing below individual atom decay

Control of reflectivity through atom density and ordering

Dynamic tuning of optical response via Bloch oscillations

Abstract

Efficient and versatile interfaces for the interaction of light with matter are an essential cornerstone for quantum science. A fundamentally new avenue of controlling light-matter interactions has been recently proposed based on the rich interplay of photon-mediated dipole-dipole interactions in structured subwavelength arrays of quantum emitters. Here we report on the direct observation of the cooperative subradiant response of a two-dimensional (2d) square array of atoms in an optical lattice. We observe a spectral narrowing of the collective atomic response well below the quantum-limited decay of individual atoms into free space. Through spatially resolved spectroscopic measurements, we show that the array acts as an efficient mirror formed by only a single monolayer of a few hundred atoms. By tuning the atom density in the array and by changing the ordering of the particles, we are able to control the cooperative response of the array and elucidate the interplay of spatial order and dipolar interactions for the collective properties of the ensemble. Bloch oscillations of the atoms out of the array enable us to dynamically control the reflectivity of the atomic mirror. Our work demonstrates efficient optical metamaterial engineering based on structured ensembles of atoms and paves the way towards the controlled many-body physics with light and novel light-matter interfaces at the single quantum level.