Observation of vortex nucleation in a rotating two-dimensional lattice of Bose-Einstein condensates

TL;DR

This study demonstrates vortex nucleation in a rotating optical lattice loaded with a Bose-Einstein condensate, revealing how vortex formation depends on lattice depth and rotation frequency, and showing vortex patterns emerge upon recombination.

Contribution

It provides experimental evidence of vortex nucleation in a rotating optical lattice and explores the dependence on lattice parameters and the formation of Josephson-coupled condensates.

Findings

Vortices nucleate linearly with rotation frequency in deep lattices.

Vortices are observed even below the critical frequency for nucleation.

Recombination of condensates reveals vortex patterns induced by effective magnetic fields.

Abstract

We report the observation of vortex nucleation in a rotating optical lattice. A 87Rb Bose-Einstein condensate was loaded into a static two-dimensional lattice and the rotation frequency of the lattice was then increased from zero. We studied how vortex nucleation depended on optical lattice depth and rotation frequency. For deep lattices above the chemical potential of the condensate we observed a linear dependence of the number of vortices created with the rotation frequency,even below the thermodynamic critical frequency required for vortex nucleation. At these lattice depths the system formed an array of Josephson-coupled condensates. The effective magnetic field produced by rotation introduced characteristic relative phases between neighbouring condensates, such that vortices were observed upon ramping down the lattice depth and recombining the condensates.