Driving phase slips in a superfluid atom circuit with a rotating weak link

TL;DR

This study demonstrates controlled phase slips in a superfluid atom circuit with a rotating weak link, revealing dynamics analogous to superconducting loops and enabling tunable critical currents in Bose-Einstein condensates.

Contribution

It introduces a method to induce and control phase slips in a superfluid atom circuit using a rotating weak link, with dynamic adjustment of the critical current.

Findings

Observation of well-defined phase slips in a BEC ring

Vortex entry occurs at higher rotation speeds

Dynamic control of the weak link affects critical current

Abstract

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 weak link and hence the critical current, a feature which is difficult to implement in superconducting or superfluid helium circuits.