Driving Phase Slips in a Superfluid Atom Circuit with a Rotating Weak Link
We have observed well-defined phase slips between quantized persistent current states around a toroidal atomic (23Na) Bose-Einstein condensate. These phase slips are induced by a weak link (a localized region of reduced superfluid density) rotated slowly around the ring. This is analogous to the behavior of a superconducting loop with a weak link in the presence of an external magnetic field. When the weak link is rotated more rapidly, well-defined phase slips no longer occur, and vortices enter into the bulk of the condensate. A noteworthy feature of this system is the ability to dynamically vary the current-phase relation of the weak link, a feature which is difficult to implement in superconducting or superfluid helium circuits.
Wright, K. C., Blakestad, R. B., Lobb, C. J., Phillips, W. D. & Campbell, G. K. Driving Phase Slips in a Superfluid Atom Circuit with a Rotating Weak Link. Phys. Rev. Lett. 110, 025302 (2013).