Consequence of superfluidity on the expansion of a rotating Bose-Einstein condensate

Abstract

We study the time evolution of a rotating condensate, that expands after being suddenly released from the confining trap, by solving the hydrodynamic equations of irrotational superfluids. For slow initial rotation speeds, $Ω_{0}$, we find that the condensate's angular velocity increases rapidly to a maximum value and this is accompanied by a minimum in the deformation of the condensate in the rotating plane. During the expansion the sample makes a global rotation of approximately $π/2$, where the exact value depends on $Ω_{0}$. This minimum deformation can serve as an easily detectable signature of superfluidity in a Bose--Einstein condensate.

4 pages, 3 figures, submitted to PRL