Simultaneous amplitude and phase damping of a kind of Gaussian states   and their separability
  We give out the time evolution solution of simultaneous amplitude and phase damping for any continuous variable state. For the simultaneous amplitude and phase damping of a wide class of two- mode entangled Gaussian states, two analytical conditions of the separability are given. One is the sufficient condition of separability. The other is the condition of PPT separability where the Peres-Horodecki criterion is applied. Between the two conditions there may exist bound entanglement. The simplest example is the simultaneous amplitude and phase damping of a two-mode squeezed vacuum state. The damped state is non-Gaussian. 
Xiao-Yu Chen