Quantized circular motion of a trapped Bose-Einstein condensate: coherent rotation and vortices

TL;DR

This paper investigates how to generate vortex states in a trapped Bose-Einstein condensate using rotating forces, highlighting the necessity of anharmonic traps and sinusoidal modulation for efficient vortex creation.

Contribution

It demonstrates that anharmonic trapping potentials are essential for creating pure vortex states and provides analytical and numerical insights into this process.

Findings

Pure vortex states require anharmonic traps.

Sinusoidal variation of angular velocity enhances vortex creation.

Analytical and numerical results support the mechanism.

Abstract

We study the creation of vortex states in a trapped Bose-Einstein condensate by a rotating force. For a harmonic trapping potential the rotating force induces only a circular motion of the whole condensate around the trap center which does not depend on the interatomic interaction. For the creation of a pure vortex state it is necessary to confine the atoms in an anharmonic trapping potential. The efficiency of the creation can be greatly enhanced by a sinusodial variation of the force's angular velocity. We present analytical and numerical calculations for the case of a quartic trapping potential. The physical mechanism behind the requirement of an anharmonic trapping potential for the creation of pure vortex states is explained. [Changes: new numerical and analytical results are added and the representation is improved.]