Multicomponent polariton superfluidity in the optical parametric oscillator regime

Abstract

Superfluidity, which is the ability of a liquid or gas to flow with zero viscosity, is one of the most remarkable implications of collective quantum coherence. In equilibrium systems such as liquid 4He and ultracold atomic gases, superfluid behavior conjugates diverse yet related phenomena, such as a persistent metastable flow in multiply connected geometries and the existence of a critical velocity for frictionless flow when hitting a static defect. The link between these different aspects of superfluid behavior is far less clear in driven-dissipative systems displaying collective coherence, such as microcavity polaritons, which raises important questions about their concurrency. With a joint theoretical and experimental study, we show that the scenario is particularly rich for polaritons driven in a three-fluid collective coherent regime, i.e., a so-called optical parametric oscillator. On the one hand, the spontaneous macroscopic coherence following the phase locking of the signal and idler fluids has been shown to be responsible for their simultaneous quantized flow metastability. On the other hand, we show here that the pump, signal, and idler have distinct responses when hitting a static defect; while the signal displays modulations that are barely perceptible, the ones appearing in the pump and idler are determined by their mutual coupling due to nonlinear and parametric processes.