Nonequilibrium transitions, chaos, and chimera states in exciton–polariton systems

The review is devoted to exciton polaritons, short-lived Bose particles which are optically excited in semiconductors and form macroscopically coherent states under conditions of coherent and resonant external driving. The interaction of polaritons results in multistability, spontaneous breaking of spin and spatial symmetries, self-pulsations, and pattern formation. As a result of symmetry breaking, paradoxical ‘chimera states’ can arise in which ordered and chaotic subsystems coexist and in some way complement each other.