Hysteresis effects in rotating Bose-Einstein condensates

TL;DR

This paper investigates how the vortex formation and angular momentum in a rotating Bose-Einstein condensate depend on the trap's rotation history, revealing hysteresis effects linked to resonance frequency shifts in the condensate's modes.

Contribution

The study introduces a hydrodynamic model explaining hysteresis in vortex formation due to resonance frequency shifts in rotating Bose-Einstein condensates.

Findings

Vortex number depends on rotation history.

Hysteresis observed between spin-up and spin-down responses.

Resonance frequency shifts explain hysteresis phenomena.

Abstract

We study the formation of vortices in a dilute Bose-Einstein condensate confined in a rotating anisotropic trap. We find that the number of vortices and angular momentum attained by the condensate depends upon the rotation history of the trap and on the number of vortices present in the condensate initially. A simplified model based on hydrodynamic equations is developed, and used to explain this effect in terms of a shift in the resonance frequency of the quadrupole mode of the condensate in the presence of a vortex lattice. Differences between the spin-up and spin-down response of the condensate are found, demonstrating hysteresis phenomena in this system.