Creation and characterization of vortex clusters in atomic Bose-Einstein condensates

TL;DR

This paper demonstrates how a moving obstacle can generate vortex clusters in 2D Bose-Einstein condensates, introduces new statistical measures for clustering analysis, and discusses experimental feasibility for creating quantum turbulence.

Contribution

It introduces novel clustering measures based on Ripley's K-function tailored for small vortex systems in BECs and extends methods to induce 2D quantum turbulence experimentally.

Findings

Vortices can be dispersed or form like-signed clusters due to a moving obstacle.

New statistical measures effectively analyze vortex clustering in small systems.

The techniques are experimentally accessible using laser beams and optical masks.

Abstract

We show that a moving obstacle, in the form of an elongated paddle, can create vortices that are dispersed, or induce clusters of like-signed vortices in 2D Bose-Einstein condensates. We propose new statistical measures of clustering based on Ripley's K-function which are suitable to the small size and small number of vortices in atomic condensates, which lack the huge number of length scales excited in larger classical and quantum turbulent fluid systems. The evolution and decay of clustering is analyzed using these measures. Experimentally it should prove possible to create such an obstacle by a laser beam and a moving optical mask. The theoretical techniques we present are accessible to experimentalists and extend the current methods available to induce 2D quantum turbulence in Bose-Einstein condensates.