Observation of long-lived polariton states in semiconductor microcavities across the parametric threshold

TL;DR

This study investigates the lifetime of polariton states in semiconductor microcavities near the parametric threshold, revealing a significant increase in lifetime due to critical slowing down and Goldstone mode emergence.

Contribution

It provides direct experimental evidence of long-lived polariton states and their behavior near the OPO threshold in semiconductor microcavities.

Findings

Lifetime increases dramatically near the threshold

Critical slowing down observed in dynamics

Emergence of soft Goldstone mode

Abstract

The excitation spectrum around the pump-only stationary state of a polariton optical parametric oscillator (OPO) in semiconductor microcavities is investigated by time-resolved photoluminescence. The response to a weak pulsed perturbation in the vicinity of the idler mode is directly related to the lifetime of the elementary excitations. A dramatic increase of the lifetime is observed for a pump intensity approaching and exceeding the OPO threshold. The observations can be explained in terms of a critical slowing down of the dynamics upon approaching the threshold and the following onset of the soft Goldstone mode.