Preservation of nonclassicality in the continuous-variable quantum teleportation

We first establish the relation between the P-function of the input and output states in the protocol of quantum teleportation of continuous variables of an optical field. We find a condition involving the squeezing parameter and the detector efficiency, under which the P-function of the output state becomes the Q function of the input state such that any nonclassical features in the input state will be eliminated in the teleported state. In particular, we notice that if the homodnye detection efficiency is less than 0.5 the teleported field must be classical even if the entanglement in the quantum channel is perfect.