Entanglement-assisted capacity of a quantum channel and the reverse Shannon theorem

The entanglement-assisted classical capacity of a noisy quantum channel ( ) is the amount of information per channel use that can be sent over the channel in the limit of many uses of the channel, assuming that the sender and receiver have access to the resource of shared quantum entanglement, which may be used up by the communication protocol. We show that the capacity is given by an expression parallel to that for the capacity of a purely classical channel: i.e., the maximum, over channel inputs , of the entropy of the channel input plus the entropy of the channel output minus their joint entropy, the latter being defined as the entropy of an entangled purification of after half of it has passed through the channel. We calculate entanglement-assisted capacities for two interesting quantum channels, the qubit amplitude damping channel and the bosonic channel with amplification/attenuation and Gaussian noise. We discuss how many independent parameters are required to completely charact...

• Type: Journal
• Year: 2002
• Where: TIT
• Authors: Charles H. Bennett, Peter W. Shor, John A. Smolin, Ashish V. Thapliyal
• Keywords: Channel Input, Noisy Quantum Channel, Quantum Channel, TIT 2002