Coexisting Non-Equilibrium Condensates with Long-Range Spatial Coherence in Semiconductor Microcavities

TL;DR

This study investigates non-equilibrium polariton condensates in semiconductor microcavities, revealing multiple coexisting modes with long-range coherence influenced by disorder and excitation conditions, supported by experimental and theoretical analysis.

Contribution

It demonstrates the coexistence of multiple non-equilibrium condensate modes with long-range coherence and provides a theoretical model explaining their behavior.

Findings

Multiple macroscopically occupied modes observed

Lower energy modes are localized by disorder

Higher energy modes are delocalized with finite k-vectors

Abstract

Real and momentum space spectrally resolved images of microcavity polariton emission in the regime of condensation are investigated under non resonant excitation using a laser source with reduced intensity fluctuations on the timescale of the exciton lifetime. We observe that the polariton emission consists of many macroscopically occupied modes. Lower energy modes are strongly localized by the photonic potential disorder on a scale of few microns. Higher energy modes have finite k-vectors and are delocalized over 10-15 microns. All the modes exhibit long range spatial coherence comparable to their size. We provide a theoretical model describing the behavior of the system with the results of the simulations in good agreement with the experimental observations. We show that the multimode emission of the polariton condensate is a result of its nonequilibrium character, the interaction with the local photonic potential and the reduced intensity fluctuations of the excitation laser.