Vortex creation during magnetic trap manipulations of spinor Bose-Einstein condensates

TL;DR

This paper explores vortex creation mechanisms in spinor Bose-Einstein condensates during magnetic trap manipulations, explaining experimental interference patterns and identifying new vortex formation processes.

Contribution

It demonstrates the possibility of creating various quantized vortices during magnetic trap splitting, offering explanations for previously observed experimental anomalies.

Findings

Doubly quantized vortices can be produced topologically in the magnetic trap.

Singly quantized vortices can form during magnetic field switching-off.

Fast splitting can generate vortices, explaining interference patterns.

Abstract

We investigate several mechanisms of vortex creation during splitting of a spinor BEC in a magnetic trap controlled by a pair of current carrying wires and bias magnetic fields. Our study is motivated by a recent MIT experiment on splitting BECs with a similar trap, where unexpected fork-like structure appeared in the interference fringes corresponding to interference of two condensates, one with and the other without a singly quantized vortex. It is well-known that in a spin-1 BEC in a quadrupole trap a doubly quantized vortex is produced topologically by a ``slow'' reversal of bias magnetic field $B_z$. We find that in the magnetic trap considered it is also possible to produce a 4- and 1-quantized vortex in a spin-1 BEC. The latter is possible, for example, during the magnetic field switching-off process. We therefore provide a possible explanation for the unexpected interference patterns in the experiment. We also give an example of the creation of singly quantized vortices due to ``fast'' splitting, which is a possible alternative mechanism of the interference pattern.