On the second-order asymptotics for entanglement-assisted communication

Publication Type:
Journal Article
Citation:
Quantum Information Processing, 2016, 15 (6), pp. 2569 - 2591
Issue Date:
2016-06-01
Full metadata record
Files in This Item:
Filename Description Size
1405.1797v2.pdfAccepted Manuscript Version260.58 kB
Adobe PDF
© 2016, Springer Science+Business Media New York. The entanglement-assisted classical capacity of a quantum channel is known to provide the formal quantum generalization of Shannon’s classical channel capacity theorem, in the sense that it admits a single-letter characterization in terms of the quantum mutual information and does not increase in the presence of a noiseless quantum feedback channel from receiver to sender. In this work, we investigate second-order asymptotics of the entanglement-assisted classical communication task. That is, we consider how quickly the rates of entanglement-assisted codes converge to the entanglement-assisted classical capacity of a channel as a function of the number of channel uses and the error tolerance. We define a quantum generalization of the mutual information variance of a channel in the entanglement-assisted setting. For covariant channels, we show that this quantity is equal to the channel dispersion and thus completely characterize the convergence toward the entanglement-assisted classical capacity when the number of channel uses increases. Our results also apply to entanglement-assisted quantum communication, due to the equivalence between entanglement-assisted classical and quantum communication established by the teleportation and super-dense coding protocols.
Please use this identifier to cite or link to this item: