Dissipation-enhanced collapse singularity of a nonlocal fluid of light in a hot atomic vapor

TL;DR

This paper investigates the complex out-of-equilibrium behavior of a nonlocal fluid of light in a hot atomic vapor, revealing that dissipation enhances collapse instabilities and identifying how nonlocal interactions depend on atomic vapor conditions.

Contribution

It demonstrates that photon losses unexpectedly promote collapse instability and characterizes the nonlocal interaction range controlled by vapor temperature and density.

Findings

Dissipation enhances collapse singularities in the fluid of light.

Nonlocal interaction range increases with atomic vapor density.

Experimental evidence links nonlocality and losses to observed instabilities.

Abstract

We study the out-of-equilibrium dynamics of a two-dimensional paraxial fluid of light using a near-resonant laser propagating through a hot atomic vapor. We observe a double shock-collapse instability: a shock (gradient catastrophe) for the velocity, as well as an annular (ring-shaped) collapse singularity for the density. We find experimental evidence that this instability results from the combined effect of the nonlocal photon-photon interaction and the linear photon losses. The theoretical analysis based on the method of characteristics reveals the main counterintuitive result that dissipation (photon losses) is responsible for an unexpected enhancement of the collapse instability. Detailed analytical modeling makes it possible to evaluate the nonlocality range of the interaction. The nonlocality is controlled by adjusting the atomic vapor temperature and is seen to increase dramatically when the atomic density becomes much larger than one atom per cubic wavelength. Interestingly, such a large range of the nonlocal photon-photon interaction has not been observed in an atomic vapor so far and its microscopic origin is currently unknown.