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

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 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.

Measurement of the Static Structure Factor in a Paraxial Fluid of Light Using Bragg-like Spectroscopy

“…Fluids of light in the paraxial configuration have emerged as an original approach to study degenerate Bose gases [1]. Several important results have recently established this platform as a potential analogue quantum simulator, including the demonstrations of superfluidity of light [2][3][4], the observation of the Berezinskii-Kosterlitz-Thouless transition [5], shockwaves [6][7][8] and precondensation [9], the evidence of photon droplets [10], and the creation of analogue rotating black hole geometries [11,12]. Paraxial fluids of light rely on the direct mathematical analogy that can be drawn between the Gross-Pitaevskii equation describing the mean field evolution of a Bose-Einstein condensate (BEC) and the nonlinear Schrödinger equation describing the propagation of light within a χ ð3Þ nonlinear medium [1,13,14].…”