Unstable and stable regimes of polariton condensation

TL;DR

This paper experimentally investigates modulational instabilities in polariton condensates, revealing how they cause coherence loss and how periodic potentials can stabilize the system, advancing understanding of quantum fluid behaviors.

Contribution

It demonstrates the existence of modulational instability in polariton condensates and shows how periodic potentials can suppress it, improving coherence and homogeneity.

Findings

Modulational instability causes reduced coherence in polariton condensates.

Periodic potentials can suppress instability and enhance coherence.

Chaotic behavior leads to inhomogeneous density distributions.

Abstract

Modulational instabilities play a key role in a wide range of nonlinear optical phenomena, leading e.g. to the formation of spatial and temporal solitons, rogue waves and chaotic dynamics. Here we experimentally demonstrate the existence of a modulational instability in condensates of cavity polaritons, arising from the strong coupling of cavity photons with quantum well excitons. For this purpose we investigate the spatiotemporal coherence properties of polariton condensates in GaAs-based microcavities under continuous-wave pumping. The chaotic behavior of the instability results in a strongly reduced spatial and temporal coherence and a significantly inhomogeneous density. Additionally we show how the instability can be tamed by introducing a periodic potential so that condensation occurs into negative mass states, leading to largely improved coherence and homogeneity. These results pave the way to the exploration of long-range order in dissipative quantum fluids of light within a controlled platform.