Build up of off-diagonal long-range order in microcavity exciton-polaritons across the parametric threshold

TL;DR

This study investigates how polariton condensates in microcavities develop long-range order and coherence properties across the parametric threshold, revealing extended coherence times and spatial coherence influenced by motional narrowing effects.

Contribution

It provides experimental evidence of the buildup of off-diagonal long-range order in polariton condensates and explores how coherence varies with condensate size and pump power.

Findings

Coherence times up to 3 ns observed above threshold

Spatial coherence extends over 40 μm, matching condensate size

Long coherence times linked to motional narrowing effects

Abstract

We report an experimental study of the spontaneous spatial and temporal coherence of polariton condensates generated in the optical parametric oscillator configuration, below and at the parametric threshold, and as a function of condensate area. Above the threshold we obtain very long coherence times (up to 3 ns) and a spatial coherence extending over the entire condensate (40 \mu m). The very long coherence time and its dependence on condensate area and pump power reflect the suppression of polariton-polariton interactions by an effect equivalent to motional narrowing.