Squeezed vacuum state in lossy channel as a squeezed thermal state

This is the authors' abstract. We don't add key points for this paper.

In this paper, we alternatively study the evolution of squeezed vacuum state (SVS) in lossy channel by virtue of the phase space method. By using the formula of Wigner function (WF) in coherent representation and [Formula: see text] representation of quantum density operator, the WF formula in lossy channel is derived. After obtaining the analytical expressions of the WFs of the lossy SVS and the squeezed thermal state (STS), we further prove the fact that the lossy SVS is equivalent to a kind of STS. Our result is useful in dealing with the light field transmission problems in the presence of losses.