Single-Photon Atomic Cooling
  We report the cooling of an atomic ensemble with light, where each atom scatters only a single photon on average. This is a general method that does not require a cycling transition and can be applied to atoms or molecules which are magnetically trapped. We discuss the application of this new approach to the cooling of hydrogenic atoms for the purpose of precision spectroscopy and fundamental tests. 
Gabriel N. Price, S. Travis Bannerman, Kirsten Viering, Edvardas   Narevicius and Mark G. Raizen