Temporally resolved second-order photon correlations of exciton-polariton Bose-Einstein condensate formation

TL;DR

This study measures second-order photon correlations with sub-3 ps resolution to observe the rapid phase transition from thermal to coherent polariton condensate in a CdTe microcavity, revealing high coherence persistence.

Contribution

It provides the first temporally resolved measurement of the ultrafast phase transition in exciton-polariton Bose-Einstein condensates.

Findings

Phase transition occurs within 3.2 ps after stimulated scattering.

The emitted light shows high coherence lasting over 100 ps.

Photon statistics confirm the rapid formation of a coherent condensate.

Abstract

Second-order time correlation measurements with a temporal resolution better than 3 ps were performed on a CdTe microcavity where spontaneous Bose-Einstein condensation is observed. After the laser pulse, the nonresonantly excited thermal polariton population relaxes into a coherent polariton condensate. Photon statistics of the light emitted by the microcavity evidences a clear phase transition from the thermal state to a coherent state, which occurs within 3.2 ps after the onset of stimulated scattering. Following this very fast transition, we show that the emission possesses a very high coherence that persists for more than 100 ps after the build-up of the condensate.