Vortex clusters in a stirred polariton condensate

TL;DR

This paper investigates how the size of a rotating potential influences vortex formation in a polariton condensate, revealing size-dependent vortex clustering phenomena under different stirring conditions.

Contribution

It demonstrates the dependence of vortex number and clustering on the size of the stirring potential in a polariton condensate, a novel insight into superfluid vortex dynamics.

Findings

Smaller traps produce single vortices.

Larger traps induce vortex clusters.

Vortex clustering occurs at specific stirring speeds.

Abstract

The response of superfluids to the external rotation, evidenced by emergence of quantised vortices, distinguishes them from conventional fluids. In this work, we demonstrate that the number of vortices in a stirred polariton condensate depends on the characteristic size of the employed rotating potential induced by the nonresonant laser excitation. For smaller sizes, a single vortex with a topological charge of +-1 corresponding to the stirring direction is formed. However, for larger optical traps, clusters of two or three co-rotating vortices appear in the narrow range of GHz stirring speed.