title: Superflow in a toroidal Bose-Einstein condensate: an atom circuit with a tunable weak link.
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.
authors.affiliation: Joint Quantum Institute, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
authors.forename: A
authors.initials: A
authors.lastname: Ramanathan
authors.forename: K C
authors.initials: KC
authors.lastname: Wright
authors.forename: S R
authors.initials: SR
authors.lastname: Muniz
authors.forename: M
authors.initials: M
authors.lastname: Zelan
authors.forename: W T
authors.initials: WT
authors.lastname: Hill
authors.forename: C J
authors.initials: CJ
authors.lastname: Lobb
authors.forename: K
authors.initials: K
authors.lastname: Helmerson
authors.forename: W D
authors.initials: WD
authors.lastname: Phillips
authors.forename: G K
authors.initials: GK
authors.lastname: Campbell