Abstract
Werner states have a host of interesting properties, which often serve to illuminate the unusual properties of quantum information. Starting from these states, one may define a family of quantum channels, known as the Holevo-Werner channels, which themselves afford several unusual properties. In this paper we use the teleportation covariance of these channels to upper bound their two-way assisted quantum and secret-key capacities. This bound may be expressed in terms of relative entropy distances, such as the relative entropy of entanglement, and also in terms of the squashed entanglement. Most interestingly, we show that the relative entropy bounds are strictly sub-additive for a sub-class of the Holevo-Werner channels, so that their regularisation provides a tighter performance. These information-theoretic results are first found for point-to-point communication and then extended to repeater chains and quantum networks, under different types of routing strategies.
Original language | English |
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Article number | 494001 |
Pages (from-to) | 1-22 |
Number of pages | 22 |
Journal | Journal of Physics A: Mathematical and Theoretical |
Volume | 51 |
DOIs | |
Publication status | Published - 9 Nov 2018 |
Bibliographical note
© 2018 IOP Publishing Ltd. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details.REVTeX. 11 pages. 8 figures