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

TL;DR

This paper investigates a four-component polariton system undergoing a BKT transition, revealing a novel state characterized by topological defect proliferation on a superfluid with algebraic coherence decay, independent of mode locking.

Contribution

It uncovers a new state of matter in multicomponent polaritons where topological defect dynamics are density-dependent and decoupled from inter-component locking.

Findings

All four components share the same BKT critical point.

Topological defect creation depends on mode density, not locking.

Observation of the defect proliferation state is experimentally feasible.

Abstract

We study a four-component polariton system in the optical parametric oscillator regime consisting of exciton/photon and signal/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 inter-component 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, characterised 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.