Classical Casimir force from a quasi-condensate of light

TL;DR

This paper demonstrates that incoherent light in a Kerr medium can form a quasi-condensate exhibiting universal coherence, leading to a Casimir-like force between plates that varies with distance.

Contribution

It introduces a classical optical analog of quantum Bose gases, showing how incoherent light can produce a Casimir-like force in a Kerr medium.

Findings

Optical quasi-condensate exhibits algebraic coherence similar to 2D Bose gases.

A Casimir-like force arises between plates, attractive at large distances.

Force behavior varies from attractive to repulsive depending on plate separation.

Abstract

We show that weakly incoherent optical beams propagating in a Kerr medium exhibit a universal algebraic coherence after a short propagation time, mimicking the quasi-long-range order of ultracold quantum Bose gases in two dimensions. If two plates are inserted in the medium, this optical quasi-condensate gives rise to a long-range Casimir-like force, attractive at large distances and repulsive at short distances.