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Driving Bose-Einstein condensate vorticity with a rotating normal cloud

P. C. Haljan·I. Coddington·P. Engels·E. A. Cornell
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Abstract

We have developed an evaporative cooling technique that accelerates the circulation of an ultra-cold $^{87}$Rb gas, confined in a static harmonic potential. As a normal gas is evaporatively spun up and cooled below quantum degeneracy, it is found to nucleate vorticity in a Bose-Einstein condensate. 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.

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P. C. Haljan, I. Coddington, P. Engels, E. A. Cornell. 2001-06-19. Driving Bose-Einstein condensate vorticity with a rotating normal cloud. https://doi.org/10.1103/physrevlett.87.210403

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