Kibble-Zurek mechanism in polariton graphene

TL;DR

This paper investigates the formation of quantum vortices in a 2D polariton condensate on a honeycomb lattice, revealing a scaling behavior consistent with linear dispersion and demonstrating vortex pinning to the lattice.

Contribution

It provides the first numerical analysis of the Kibble-Zurek mechanism in polariton graphene, highlighting the impact of lattice-modified dispersion on defect formation.

Findings

Scaling exponent for defect density is approximately 0.95

Vortices can be pinned to the lattice, aiding observation

The defect formation aligns with linear dispersion predictions

Abstract

We study the formation of topological defects (quantum vortices) during the formation of a 2D polariton condensate at the $\Gamma$ point of a honeycomb lattice via the Kibble-Zurek mechanism. The lattice modifies the single-particle dispersion. The typical interaction energies at the quench time correspond to the linear part of the dispersion. The resulting scaling exponent for the density of topological defects is numerically found as $0.95\pm0.05$. This value differs from the one expected for 2D massive particles (1/2), but is indeed compatible with the one expected for a linear dispersion. We moreover demonstrate that the vortices can be pinned to the lattice, which prevents their recombination and could facilitate their observation and counting in continuous wave experiments.