On the absence of the electrostriction force in dilute clouds of cold atoms

TL;DR

This paper demonstrates both experimentally and theoretically that dilute clouds of ultra-cold atoms do not experience electrostriction forces during light refraction, challenging previous claims of such momentum transfer.

Contribution

The study provides new evidence that refraction in dilute cold atom clouds does not produce electrostriction forces, clarifying the nature of light-matter momentum transfer.

Findings

Refraction does not induce momentum transfer to first order.

Experimental results contradict previous claims of electrostriction.

Theoretical analysis supports the absence of electrostriction forces.

Abstract

The momentum of light in a medium and the mechanisms of momentum transfer between light and dielectrics have long been the topic of controversies and confusion. We discuss here the problem of momentum transfers that follow the refraction of light by dilute, inhomogeneous ensembles of ultra-cold atoms. We show experimentally and theoretically that the refraction of light rays by a dilute gas does not entail momentum transfers to first order in the light-atom coupling coefficient, in contradiction with the work reported in Matzliah et al. Phys. Rev. Lett. 119, 189902 (2017).