Heterodyne non-demolition measurements on cold atomic samples: towards   the preparation of non-classical states for atom interferometry
  We report on a novel experiment to generate non-classical atomic states via quantum non-demolition (QND) measurements on cold atomic samples prepared in a high finesse ring cavity. The heterodyne technique developed for the QND detection exhibits an optical shot-noise limited behavior for local oscillator optical power of a few hundred \muW, and a detection bandwidth of several GHz. This detection tool is used in single pass to follow non destructively the internal state evolution of an atomic sample when subjected to Rabi oscillations or a spin-echo interferometric sequence. 
Simon Bernon (LCFIO), Thomas Vanderbruggen (LCFIO), Ralf Kohlhaas   (LCFIO), Andrea Bertoldi (LCFIO), Arnaud Landragin (SYRT...
quant-ph