Quantum properties of a parametric four-wave mixing in a Raman-type   atomic system
  We present a study of the quantum properties of two light fields used to parametric four-wave mixing in a Raman-type atomic system. The system realizes an effective Hamiltonian of beamsplitter type coupling between the light fields, which allows to control squeezing and amplitude distribution of the light fields, as well as realizing their entanglement. The scheme can be feasibly applied to engineer the quantum properties of two single-mode light fields in properly chosen input states. 
A.V. Sharypov, Bing He, V.G. Arkhipkin, S.A. Myslivets
quant-ph physics.optics