On classification of quantum channels (Q2747998)

Quantum channels can be thought of as devices which transfer quantum states from an input system to an output system, and they are involved in optical communication processes. The purpose of the present paper is to classify quantum channels by using the relations between input and output optical states and to compare them in terms of quantum capacity. The optical states considered are the photon number state, the coherent state and the squeezed state. The corresponding quantum channels are defined. The concepts of quantum mutual entropy and of quantum capacity are borne in mind and then one determines the value of the quantum capacity for squeezed channels.