Renormalization group analysis of near-field induced dephasing of optical spin waves in an atomic medium

TL;DR

This paper develops a non-perturbative renormalization group theory to analyze how near-field interactions cause density-dependent dephasing of optical spin waves in dense atomic media, extending understanding beyond previous dilute and short-time approximations.

Contribution

It introduces a novel strong disorder renormalization group approach to model dephasing dynamics at arbitrary times and densities, capturing many-atom effects with an effective single-atom model.

Findings

Near-field interactions dominate dephasing in dense atomic media.

The theory accurately predicts dephasing behavior across various densities.

Results highlight limits on quantum optical phenomena due to microscopic interactions.

Abstract

While typical theories of atom-light interactions treat the atomic medium as being smooth, it is well-known that microscopic optical effects driven by atomic granularity, dipole-dipole interactions, and multiple scattering can lead to important effects. Recently, for example, it was experimentally observed that these ingredients can lead to a fundamental, density-dependent dephasing of optical spin waves in a disordered atomic medium. Here, we go beyond the short-time and dilute limits considered previously, to develop a comprehensive theory of dephasing dynamics for arbitrary times and atomic densities. In particular, we develop a novel, non-perturbative theory based on strong disorder renormalization group, in order to quantitatively predict the dominant role that near-field optical interactions between nearby neighbors has in driving the dephasing process. This theory also enables one to capture the key features of the many-atom dephasing dynamics in terms of an effective single-atom model. These results should shed light on the limits imposed by near-field interactions on quantum optical phenomena in dense atomic media, and illustrate the promise of strong disorder renormalization group as a method of dealing with complex microscopic optical phenomena in such systems.