Coherence expansion and polariton condensate formation in a semiconductor microcavity

TL;DR

This study investigates how the first order spatial coherence of polaritons expands in a high-Q GaAs microcavity during Bose-Einstein condensation, revealing a constant expansion velocity and the influence of relaxation processes.

Contribution

It provides new insights into the dynamics of coherence expansion and condensate formation in polariton systems under pulsed excitation.

Findings

Coherence expands at about 10^8 cm/s during condensate formation.

Measured coherence is lower than in thermal equilibrium during growth.

Coherence exceeds equilibrium levels after condensate decay.

Abstract

The dynamics of the expansion of the first order spatial coherence g(1) for a polariton system in a high-Q GaAs microcavity was investigated on the basis of Young's double slit experiment under 3 ps pulse excitation at the conditions of polariton Bose-Einstein condensation. It was found that in the process of condensate formation the coherence expands with a constant velocity of about 10^8 cm/s. The measured coherence is smaller than that in thermally equilibrium system during the growth of condensate density and well exceeds it at the end of condensate decay. The onset of spatial coherence is governed by polariton relaxation while condensate amplitude and phase fluctuations are not suppressed.