Converse bounds for quantum and private communication over Holevo-Werner channels

Thomas P.W. Cope, Kenneth Goodenough, Stefano Pirandola

Research output: Contribution to journalArticleScientificpeer-review

8 Citations (Scopus)


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 subadditive for a sub-class of the Holevo-Werner channels, so that their regularization 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 languageEnglish
Article number494001
Number of pages22
JournalJournal of Physics A: Mathematical and Theoretical
Issue number49
Publication statusPublished - 2018


  • entanglement measures
  • quantum capacities
  • quantum channels
  • quantum networks
  • quantum repeaters
  • teleportation
  • Werner states


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