Unconventional Berezinskii-Kosterlitz-Thouless Transition in the Multicomponent Polariton System

We study a four-component polariton system in the optical parametric oscillator regime consisting of exciton, photon, signal, and idler modes across the Berezinskii-Kosterlitz-Thouless (BKT) transition. We show that all four components share the same BKT critical point, and algebraic decay of spatial coherence with the same critical exponent. However, while the collective excitations in different components are strongly locked, both close to and far from criticality, the spontaneous creation of topological defects in the vicinity of the phase transition is found to be largely independent of the intercomponent mode locking, and instead strongly dependent on the density within a given mode. This peculiar characteristic allows us to reveal a novel state of matter, characterized by configurations of topological defects proliferating on top of a superfluid with algebraic decay of coherence, observation of which is demonstrated to be within reach of current experiments.

Automated summary

We investigate a four-component polariton system in the optical parametric oscillator regime and find that all four components exhibit the same BKT critical point and algebraic decay of spatial coherence. However, the creation of topological defects near the phase transition is largely independent of intercomponent mode locking and strongly depends on the density within a given mode. This unique characteristic allows us to discover a novel state of matter characterized by the proliferation of topological defects on a superfluid with algebraic decay of coherence, which can be observed in current experiments.