Storage of light in atomic vapor
  We report an experiment in which a light pulse is decelerated and trapped in a vapor of Rb atoms, stored for a controlled period of time, and then released on demand. We accomplish this storage of light by dynamically reducing the group velocity of the light pulse to zero, so that the coherent excitation of the light is reversibly mapped into a collective Zeeman (spin) coherence of the Rb vapor. 
D. F. Phillips, A. Fleischhauer, A. Mair, R. L. Walsworth, M. D. Lukin