Instability-induced formation and non-equilibrium dynamics of phase defects in polariton condensates

TL;DR

This paper investigates the formation and dynamics of phase defects in polariton condensates caused by modulational instability, revealing mechanisms of vortex destabilization, defect formation, and their scaling with pumping rate.

Contribution

It provides a theoretical and numerical analysis of instability regimes and defect dynamics in both scalar and spinor polariton condensates, highlighting new defect formation mechanisms.

Findings

Identification of instability regimes in scalar and spinor condensates

Observation of vortex destabilization and spiraling wave formation

Scaling of defect density with pumping rate

Abstract

We study, theoretically and numerically, the onset and development of modulational instability in an incoherently pumped spatially homogeneous polariton condensate. Within the framework of mean-field theory, we identify regimes of modulational instability in two cases: 1) Strong feedback between the condensate and reservoir, which may occur in scalar condensates, and 2) Parametric scattering in the presence of polarization splitting in spinor condensates. In both cases we investigate the instability induced textures in space and time including non-equilibrium dynamics of phase dislocations and vortices. In particular we discuss the mechanism of vortex destabilization and formation of spiraling waves. We also identify the presence of topological defects, which take the form of half-vortex pairs in the spinor case, giving an "eyelet" structure in intensity and dipole type structure in the spin polarization. In the modulationally stable parameter domains, we observe formation of the phase defects in the process of condensate formation from an initially spatially incoherent low-density state. In analogy to the Kibble-Zurek type scaling for nonequilibrium phase transitions, we find that the defect density scales with the pumping rate.