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

Journal Article (2018)
Author(s)

Thomas P.W. Cope (University of York)

K. Goodenough (TU Delft - QuTech Advanced Research Centre, TU Delft - QID/Wehner Group)

Stefano Pirandola (Massachusetts Institute of Technology, University of York)

Research Institute
QuTech Advanced Research Centre
DOI related publication
https://doi.org/10.1088/1751-8121/aae964
More Info
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Publication Year
2018
Language
English
Research Institute
QuTech Advanced Research Centre
Issue number
49
Volume number
51

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 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.

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