Two cavity modes in a dissipative environment: cross decay rates and   robust states
  We investigate the role of the cross decay rates in a system composed by two electromagnetic modes interacting with the same reservoir. Two feasible experiments sensitive to the magnitudes and phases of these rates are described. We show that if the cross decay rates are appreciable there are states less exposed to decoherence and dissipation, and in limit situations a decoherence free subspace appears. 
R. Rossi Jr, A. R. Bosco de Magalh\~aes, M. C. Nemes