Instabilities of off-centered vortices in a Bose-Einstein condensate

Abstract

We study numerically the excitations of off-centered vortices in a Bose-Einstein condensate. The displacement of a single vortex and the separation of a doubly quantized vortex are considered. We find that the core-localized excitations of the precessing vortices continue to feature the property which implies that the vortices are unstable. The core-localized, dipolar, and quadrupolar excitations are found to deform continuously as functions of vortex displacements and intervortex separation.

8 pages, 9 figures. Introduction and Conclusion are fully revised. Definitions of angular momenta and usage of the time-dependent Bogoliubov Eqs. are newly clarified