Demonstration of an inductively coupled ring trap for cold atoms
  We report the first demonstration of an inductively coupled magnetic ring trap for cold atoms. A uniform, ac magnetic field is used to induce current in a copper ring, which creates an opposing magnetic field that is time-averaged to produce a smooth cylindrically symmetric ring trap of radius 5 mm. We use a laser-cooled atomic sample to characterise the loading efficiency and adiabaticity of the magnetic potential, achieving a vacuum-limited lifetime in the trap. This technique is suitable for creating scalable toroidal waveguides for applications in matterwave interferometry, offering long interaction times and large enclosed areas. 
J. D. Pritchard, A. N. Dinkelaker, A. S. Arnold, P. F. Griffin and E.   Riis
physics.atom-ph