Private States, Quantum Data Hiding, and the Swapping of Perfect Secrecy

Matthias Christandl and Roberto Ferrara
Phys. Rev. Lett. 119, 220506 – Published 30 November 2017
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Abstract

An important contribution to the understanding of quantum key distribution has been the discovery of entangled states from which secret bits, but no maximally entangled states, can be extracted [Horodecki et al., Phys. Rev. Lett. 94, 200501 (2005)]. The construction of those states was based on an intuition that the quantum mechanical phenomena of data hiding and privacy might be related. In this Letter we firmly connect these two phenomena and highlight three aspects of this result. First, we simplify the definition of the secret key rate. Second, we give a formula for the one-way distillable entanglement of certain private states. Third, we consider the problem of extending the distance of quantum key distribution with help of intermediate stations, a setting called the quantum key repeater. We show that for protocols that first distill private states, it is essentially optimal to use the standard quantum repeater protocol based on entanglement distillation and entanglement swapping.

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  • Received 14 October 2016

DOI:https://doi.org/10.1103/PhysRevLett.119.220506

© 2017 American Physical Society

Physics Subject Headings (PhySH)

Quantum Information, Science & Technology

Authors & Affiliations

Matthias Christandl* and Roberto Ferrara

  • QMATH, Department of Mathematical Sciences, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, Denmark

  • *christandl@math.ku.dk
  • roberto@math.ku.dk

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Issue

Vol. 119, Iss. 22 — 1 December 2017

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