Superflow in a toroidal Bose-Einstein condensate: an atom circuit with a tunable weak link |
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Authors: | Ramanathan A Wright K C Muniz S R Zelan M Hill W T Lobb C J Helmerson K Phillips W D Campbell G K |
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Affiliation: | Joint Quantum Institute, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA. |
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Abstract: | We have created a long-lived (≈40 s) persistent current in a toroidal Bose-Einstein condensate held in an all-optical trap. A repulsive optical barrier across one side of the torus creates a tunable weak link in the condensate circuit, which can affect the current around the loop. Superflow stops abruptly at a barrier strength such that the local flow velocity at the barrier exceeds a critical velocity. The measured critical velocity is consistent with dissipation due to the creation of vortex-antivortex pairs. This system is the first realization of an elementary closed-loop atom circuit. |
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