Continuous pumping and control of mesoscopic superposition state in a   lossy QED cavity
  Here we consider the continuous pumping of a dissipative QED cavity and derive the time-dependent density operator of the cavity field prepared initially as a superposition of mesoscopic coherent states. The control of the coherence of this superposition is analyzed considering the injection of a beam of two-level Rydberg atoms through the cavity. Our treatment is compared to other approaches. 
M. C. de Oliveira, M. H. Y. Moussa, and S. S. Mizrahi