Effective field theory of resonant 2-level atoms
  The phenomenological two-level atom is re-analysed using the methods of effective field theory. By presenting the Dicke-Jaynes-Cummings model in real space, an exact diagonalization is accomplished going beyond the rotating wave approximation. The meaning of the symmetries and conserved quantities in the theory is discussed and the model is related to non-equilibrium field theory. The structure of the solution raises a question about the rotating wave approximation in quantum mechanics. 
Mark Burgess