  In a recent study we demonstrated the emergence of turbulence in a trapped
Bose-Einstein condensate of Rb-87 atoms. An intriguing observation in such a
system is the behavior of the turbulent cloud during free expansion.The aspect
ratio of the cloud size does not change in the way one would expect for an
ordinary non-rotating (vortex-free) condensate. Here we show that the anomalous
expansion can be understood, at least qualitatively, in terms of the presence
of vorticity distributed throughout the cloud, effectively counteracting the
usual reversal of the aspect ratio seen in free time-of-flight expansion of
non-rotating condensates.

Quantum Gases;Atomic Physics;Fluid Dynamics