Subradiance-protected excitation spreading in the generation of collimated photon emission from an atomic array

TL;DR

This paper demonstrates how to convert localized atomic excitations into highly directional, long-lived subradiant modes in a 2D atomic array, enabling controlled photon emission for quantum information applications.

Contribution

It introduces a method to generate and control subradiant eigenmodes in atomic arrays for directional photon emission, advancing quantum communication techniques.

Findings

Achieved long-lived subradiant modes in atomic arrays.

Controlled the release of excitations via Zeeman level shifts.

Enabled highly directional photon emission along a specific axis.

Abstract

We show how an initial localized radiative excitation in a two-dimensional array of cold atoms can be converted into highly-directional coherent emission of light by protecting the spreading of the excitation across the array in a subradiant collective eigenmode with a lifetime orders of magnitude longer than that of an isolated atom. We demonstrate how to reach two such strongly subradiant modes, a uniform one where all the dipoles are oscillating in phase normal to the plane and an antiferromagnetic mode where each dipole is $\pi$ out of phase with its nearest neighbor. The excitation, which can consist of a single photon, is then released from the protected subradiant eigenmode by controlling the Zeeman level shifts of the atoms. Hence, an original localized excitation which emits in all directions is transferred to a delocalized subradiance-protected excitation, with a probabilistic emission of a photon only along the axis perpendicular to the plane of the atoms. This protected spreading and directional emission could potentially be used to link stages in a quantum information or quantum computing architecture.