Rotating a Bose-Einstein condensate using photons with orbital angular momentum
Kristian Helmerson, Mikkel F. Andersen, Changhyun Ryu +5 more
We demonstrate the coherent transfer of the orbital angular momentum of a photon to an atom in quantized units of h, using a 2-photon stimulated Raman process with Laguerre-Gaussian beams to generate an atomic vortex state in a Bose-Einstein condensate of sodium atoms. We show that the process is coherent by creating superpositions of different vortex states, where the relative phase between the states is determined by the relative phases of the optical fields. Furthermore, we create vortices of charge 2 by transferring to each atom the orbital angular momentum of two photons. We subsequently use our technique to induce rotation of the condensate confined in an asymmetric, ring-shaped hybrid optical and magnetic trap. We observe the cloud rotating for up to 13 seconds, due to the superfluid character of the condensate.
Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Aug 31, 2006•2 citations