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

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 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 is observed in an atomic vapor here, but its microscopic origin is currently unknown.

Automated summary

The study reveals a double shock-collapse instability in a two-dimensional paraxial fluid of light when using a near-resonant laser propagating through hot atomic vapor. This instability is found to result from the combined effect of nonlocal photon-photon interaction and linear photon losses, with dissipation unexpectedly enhancing the collapse instability. Adjustment of atomic vapor temperature controls the nonlocality range of the interaction, which increases significantly with higher atomic density.