Vortex formation in a fast rotating Bose-Einstein condensate

TL;DR

This paper investigates how vortex formation occurs in a rotating Bose-Einstein condensate confined in a combined harmonic and quartic potential, highlighting the role of interactions and potential shape in symmetry breaking and vortex creation.

Contribution

It demonstrates that vortex formation in attractive or non-interacting condensates requires a quartic potential and analyzes the conditions for spontaneous shape deformation leading to vortices.

Findings

Vortex formation is enabled by a quartic potential in attractive condensates.

Symmetry breaking occurs when rotational frequency exceeds half the surface mode frequency.

Shape deformation and vortex formation depend on interaction strength and potential parameters.

Abstract

We study rotational motion of an interacting atomic Bose-Einstein condensate confined in a quadratic-plus-quartic potential. We calculate the lowest energy surface mode frequency and show that a symmetric trapped (harmonic and quartic) Bose-Einstein condensate breaks the rotational symmetry of the Hamiltonian when rotational frequency is greater than one-half of the lowest energy surface mode frequency. We argue that the formation of a vortex is not possible in a non-interacting as well as in an attractive Bose-Einstein condensate confined in a harmonic trap due to the absence of the spontaneous shape deformation, but it can occur which leads to the vortex formation if we add an additional quartic potential. Moreover, the spontaneous shape deformation and consequently the formation of a vortex in an attractive system depends on the strengths of the two-body interaction and the quartic potential.