Multi-stability and condensation of exciton-polaritons below threshold

TL;DR

This paper investigates the complex dynamics of exciton-polariton condensates in a pumped Josephson junction, revealing multi-stability, PT symmetry effects, and condensation phenomena below the traditional threshold, with implications for experimental observations.

Contribution

It introduces a mean-field model for a pumped polariton Josephson junction, demonstrating multi-stability, PT symmetry influence, and sub-threshold condensation, advancing understanding of long-term nonlinear polariton dynamics.

Findings

Multi-stability of stationary states due to Josephson current.

Sensitivity of states to initial conditions and noise.

Prediction of condensation below threshold with hysteresis.

Abstract

Exciton-polaritons can condense to a macroscopic quantum state through a non-equilibrium process of pumping and decay. In recent experiments, polariton condensates are used to observe, for a short time, nonlinear Josephson phenomena by coupling two condensates. However, it is still not clear how these phenomena are affected by the pumping and decay at long times and how the coupling alters the polariton condensation. Here, we consider a polariton Josephson junction pumped on one side and study its dynamics within a mean-field theory. The Josephson current is found to give rise to multi-stability of the stationary states, which are sensitive to the initial conditions and incoherent noises. These states can be attributed to either the self-trapping effect or the parity-time (PT) symmetry of the system. These results can be used to explain the emission spectra and the $\pi$-phase locking observed in recent experiments. We further predict that the multi-stability can reduce to the self-trapped state if the PT symmetry is broken. Moreover, the polaritons can condense even below the threshold, exhibiting hysteresis.