Stochastic precession of the polarization in a polariton laser

TL;DR

This paper investigates the polarization dynamics of polariton lasing in GaAs microcavities, revealing stochastic initial polarization states, intrinsic polarization splitting, and minimal influence of polariton interactions on emission statistics.

Contribution

It demonstrates the stochastic nature of initial polarization in polariton lasing and identifies intrinsic polarization splitting using ultrafast detection, highlighting the negligible role of polariton interactions.

Findings

Initial polarization is stochastic and can take any direction on the Poincaré sphere.

Polariton lasing exhibits high second-order coherence ($g^{(2)}(0) \\approx 1$).

Intrinsic polarization splitting causes subsequent polarization oscillations.

Abstract

Microcavity polaritons in the lasing regime undergo a spontaneous symmetry breaking transition resulting in coherent emission with a well defined polarization. The order parameter is thus a vector describing both the laser global phase and polarization. Using an ultrafast single-shot detection technique we show that polariton lasing in GaAs-based microcavities presents a high degree of second order coherence ($g^{(2)}(\tau=0) \approx 1$) above threshold, and that the initial polarization is stochastic, taking any possible direction in the Poincar\'e sphere (linear, elliptical or circular). Once the polarization direction is established, subsequent oscillations of the emission probability witness the presence of an intrinsic polarization splitting. Our results show the negligible role of polariton interactions in the total emission statistics and in the establishment of the initial polarization.