QUANTUM CAPACITY OF NOISY QUANTUM CHANNEL

摘要

In quantum communication theory, the quantum mutual entropy is an important tool to analyse the efficiency of information transmission. It is the amount of information correctly transmitted from an input system to an output system through a quantum channel. The supremum of the quantum mutual entropy over a certain set of states with a fixed quantum channel is the quantum capacity of the channel. The capacity for quantum systems has been discussed in several papers, like. In, we studied the quantum capacity for purely quantum channels.rnIn this paper, we briefly review quantum channels and quantum mutual entropy and we show a useful proposition to calculate the quantum mutual entropy in §2. In §3, we explain the capacity of quantum channels in. In §4, we compute the quantum capacity of a noisy quantum channel with respect to a subset of the state space under a certain energy constraint.