Nonequilibrium Prethermal States in a Two-Dimensional Photon Fluid

We report on the observation of a prethermal state in a nonequilibrium, two-dimensional fluid of light. Direct measurements of the first order coherence function of the fluid reveal the dynamical emergence of algebraic correlations, a quasi-steady-state with properties close to those of thermal superfluids. By a controlled increase of the fluctuations, we observe a crossover from algebraic to short-range (exponential) correlations. We interpret this phenomenon as a nonequilibrium precursor of the Kosterlitz-Thouless transition.

Automated summary

We report on the observation of a prethermal state in a nonequilibrium, two-dimensional fluid of light. By directly measuring the first order coherence function of the fluid, we observe the emergence of algebraic correlations, which resemble the properties of thermal superfluids. Increasing the fluctuations leads to a transition from algebraic to short-range correlations. This phenomenon is interpreted as a nonequilibrium precursor of the Kosterlitz-Thouless transition.