Accessing Kardar-Parisi-Zhang universality sub-classes with exciton polaritons.

Exciton-polariton condensates under driven-dissipative conditions are predicted to belong to the Kardar-Parisi-Zhang (KPZ) universality class, the dynamics of the condensate phase satisfying the same equation as for classical stochastic interface growth at long distance. We show that by engineering an external confinement for one-dimensional polaritons we can access two different universality sub-classes, which are associated to the flat or curved geometry for the interface. Our results for the condensate phase distribution and correlations match with great accuracy with the exact theoretical results for KPZ: the Tracy-Widom distributions (GOE and GUE) for the one-point statistics, and covariance of Airy processes (Airy1 and Airy2) for the two-point statistics. This study promotes the exciton-polariton system as a compelling platform to investigate KPZ universal properties.