Annular Vortex Chain in a Resonantly Pumped Polariton Superfluid

TL;DR

This paper demonstrates the formation of a ring-shaped array of vortices in a polariton superfluid induced by angular momentum injection using a Laguerre-Gauss beam, revealing nonlinear vortex nucleation and dynamics.

Contribution

It introduces a novel method to generate and study vortex chains in polariton superfluids via resonant optical pumping with angular momentum.

Findings

Vortices form a ring-shaped array after angular momentum injection.

Vortex nucleation occurs due to angular momentum quantization in the nonlinear regime.

Spontaneous vortex-antivortex pairs emerge from hydrodynamic instabilities.

Abstract

We report the formation of a ring-shaped array of vortices after injection of angular momentum in a polariton superfluid. The angular momentum is injected by a $\ell= 8$ Laguerre-Gauss beam, whereas the global rotation of the fluid is hindered by a narrow Gaussian beam placed at its center. In the linear regime a spiral interference pattern containing phase defects is visible. In the nonlinear (superfluid) regime, the interference disappears and the vortices nucleate as a consequence of the angular momentum quantization. The radial position of the vortices evolves freely in the region between the two pumps as a function of the density. Hydrodynamic instabilities resulting in the spontaneous nucleation of vortex-antivortex pairs when the system size is sufficiently large confirm that the vortices are not constrained by interference when nonlinearities dominate the system.