Unitary reduction of the Liouville equation relative to a two-level atom   coupled to a bimodal lossy cavity
  The Liouville equation of a two-level atom coupled to a degenerate bimodal lossy cavity is unitarily and exactly reduced to two uncoupled Liouville equations. The first one describes a dissipative Jaynes-Cummings model and the other one a damped harmonic oscillator. Advantages related to the reduction method are discussed. 
A. Napoli, Xiang-ming Hu, A. Messina