Searching for Decoherence-Free Subspaces in Cavity Quantum   Electrodynamics
  We construct a model which describes a recently performed experiment (Phys. Rev. A 64, 050301(R) (2001)) in which an entangled state between two modes of a single cavity is built. Environmental effects are taken into account and the results agree with the experimental findings. Moreover the model predicts, for different conditions of the same experiment, a decoherence-free subspace. These conditions are analyzed and slightly different experiments suggested in order to test its viability. 
A. R. Bosco de Magalh\~aes, and M.C. Nemes