Spin Squeezing via One-Axis Twisting with Coherent Light
  We propose a new method of spin squeezing of atomic spin, based on the interactions between atoms and off-resonant light which are known as paramagnetic Faraday rotation and fictitious magnetic field of light. Since the projection process, squeezed light, or special interactions among the atoms are not required in this method, it can be widely applied to many systems. The attainable range of the squeezing parameter is S^{-2/5}, where S is the total spin, which is limited by additional fluctuations imposed by coherent light and the spherical nature of the spin distribution. 
M.Takeuchi, S.Ichihara, T.Takano, M.Kumakura, T.Yabuzaki, and   Y.Takahashi