Atomic-phase interference devices based on ring-shaped Bose-Einstein   condensates: Two ring case
  We theoretically investigate the ground-state properties and quantum dynamics of a pair of adjacent ring-shaped Bose-Einstein condensates that are coupled via tunneling. This device, which is the analogue of a symmetric superconducting quantum interference device, is the simplest version of what we term an Atomic-Phase Interference Device (APHID). The two-ring APHID is shown to be sensitive to rotation. 
B. P. Anderson, K. Dholakia, E. M. Wright