Superradiant detection of microscopic optical dipolar interactions

TL;DR

This paper introduces a method to detect microscopic optical dipolar interactions in cold atoms by temporarily suppressing macroscopic light propagation, enabling precise characterization of density-dependent dephasing effects.

Contribution

The authors develop a background-free detection technique that isolates microscopic dynamics from superradiant emission in cold atomic ensembles.

Findings

Successfully suppresses macroscopic propagation effects

Reveals density-dependent dipolar dephasing

Enhances understanding of atom-light interface limitations

Abstract

The interaction between light and cold atoms is a complex phenomenon potentially featuring many-body resonant dipole interactions. A major obstacle toward exploring these quantum resources of the system is macroscopic light propagation effects, which not only limit the available time for the microscopic correlations to locally build up, but also create a directional, superradiant emission background whose variations can overwhelm the microscopic effects. In this Letter, we demonstrate a method to perform ``background-free'' detection of the microscopic optical dynamics in a laser-cooled atomic ensemble. This is made possible by transiently suppressing the macroscopic optical propagation over a substantial time, before a recall of superradiance that imprints the effect of the accumulated microscopic dynamics into an efficiently detectable outgoing field. We apply this technique to unveil and precisely characterize a density-dependent, microscopic dipolar dephasing effect that generally limits the lifetime of optical spin-wave order in ensemble-based atom-light interfaces.