Dynamic and Energetic Stabilization of Persistent Currents in Bose-Einstein Condensates

Abstract

We study conditions under which vortices in a highly oblate harmonically trapped Bose-Einstein condensate (BEC) can be stabilized due to pinning by a blue-detuned Gaussian laser beam, with particular emphasis on the potentially destabilizing effects of laser beam positioning within the BEC. Our approach involves theoretical and numerical exploration of dynamically and energetically stable pinning of vortices with winding number up to $S=6$, in correspondence with experimental observations. Stable pinning is quantified theoretically via Bogoliubov-de Gennes excitation spectrum computations and confirmed via direct numerical simulations for a range of conditions similar to those of experimental observations. The theoretical and numerical results indicate that the pinned winding number, or equivalently the winding number of the superfluid current about the laser beam, decays as a laser beam of fixed intensity moves away from the BEC center. Our theoretical analysis helps explain previous experimental observations, and helps define limits of stable vortex pinning for future experiments involving vortex manipulation by laser beams.

8 pages 5 figures

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• Generating and Manipulating Quantized Vortices On-Demand in a Bose-Einstein Condensate: a Numerical Study
• Persistent currents in ultracold gases
• Generation of high winding-number superfluid circulation in Bose-Einstein condensates
• Superfluid flow past an obstacle in annular Bose--Einstein condensates
• Pairwise Interactions of Ring Dark Solitons with Vortices and other Rings: Stationary States, Stability Features and Nonlinear Dynamics
• Stability and dynamics of massive vortices in two-component Bose-Einstein condensates
• Stability change of a multi-charged vortex due to coupling with quadrupole mode