Cooperative scattering and radiation pressure force in dense atomic clouds

TL;DR

This paper analyzes collective scattering and radiation pressure in dense atomic clouds, deriving analytical expressions for key quantities and comparing them with exact solutions, highlighting effects beyond symmetric states.

Contribution

It introduces a continuum approach to describe atom-atom interactions in dense clouds, accounting for back action and refraction effects not captured by symmetric timed Dicke states.

Findings

Analytical expressions for scattered intensity and radiation pressure force.

Comparison shows deviations from symmetric timed Dicke state predictions.

Back action and refraction significantly affect scattering behavior.

Abstract

We consider the collective scattering by a cloud of $N$ two-level atoms driven by an uniform radiation field. Dense atomic clouds can be described by a continuous density and the problem reduces to deriving the spectrum of the atom-atom coupling operator. For clouds much larger than the optical wavelength, the spectrum is treated as a continuum, and analytical expressions for several macroscopic quantities, such as scattered radiation intensity and radiation pressure force, are derived. The analytical results are then compared to the exact $N$-body solution and with those obtained assuming a symmetric timed Dicke state. In contrast with the symmetric timed Dicke state, our calculations takes account of the back action of the atoms on the driving field leading to phase shifts due to the finite refraction of the cloud.