Driving Bose-Einstein-Condensate Vorticity With a Rotating Normal Cloud
P C. Haljan, Ian R. Coddington, P Engels, Eric A. Cornell
We have developed an evaporative cooling technique that accelerates the circulation of an ultra-cold 87Rb gas, confined in a static harmonicpotential. As a normal gas is evaporatively spun up and cooled below quantum degeneracy, it is found to nucleate vorticity in a Bose-Einsteincondensate. Measurements of the condensate's aspect ratio and surface-wave excitations are consistent with effective rigid-body rotation.Rotation rates of up to 94% of the centrifugal limit are inferred. A threshold in the normal cloud's rotation is observed for the intrinsic nucleation of the first vortex. The threshold value lies below the prediction for a nucleation mechanism involving the excitation of surface waves of the ground-state condensate.
Physical Review Letters
Bose-Einstein condensation, superfluidity
, Coddington, I.
, Engels, P.
and Cornell, E.
Driving Bose-Einstein-Condensate Vorticity With a Rotating Normal Cloud, Physical Review Letters
(Accessed December 3, 2023)