The quantum theory of polariton condensation in a trapped state reveals a second-order phase transition evidenced by spontaneous polarization parity breaking in sub-spaces of fixed polariton occupation numbers. The emission spectra of a polariton condensate demonstrate the coexistence of a symmetry-conserving condensate state with {linear} polarization and two symmetry-broken elliptically polarized states in the vicinity of the threshold. As a result, an oscillating linearly polarized second-order coherence gxx(2)(t), with gxx(2)(t)<1 over some time intervals is obtained. Spontaneous symmetry breaking is reflected in the second-order cross correlator of circular polarizations. A related build-up of elliptically-polarized weak lasing also results in non-monotonous dependence of the circular second-order coherence on excitation power and interaction strength.
@article{arxiv.2310.16166,
title = {Quantum theory of polariton weak lasing and polarization bifurcations},
author = {Huawen Xu and Timothy C. H. Liew and Yuri G. Rubo},
journal= {arXiv preprint arXiv:2310.16166},
year = {2024}
}