One-way quantum key distribution: Simple upper bound on the secret key rate

Tobias Moroder, Marcos Curty, and Norbert Lütkenhaus
Phys. Rev. A 74, 052301 – Published 1 November 2006

Abstract

We present a simple method to obtain an upper bound on the achievable secret key rate in quantum key distribution (QKD) protocols that use only unidirectional classical communication during the public-discussion phase. This method is based on a necessary precondition for one-way secret key distillation; the legitimate users need to prove that there exists no quantum state having a symmetric extension that is compatible with the available measurements results. The main advantage of the obtained upper bound is that it can be formulated as a semidefinite program, which can be efficiently solved. We illustrate our results by analyzing two well-known qubit-based QKD protocols: the four-state protocol and the six-state protocol.

  • Figure
  • Received 18 April 2006

DOI:https://doi.org/10.1103/PhysRevA.74.052301

©2006 American Physical Society

Authors & Affiliations

Tobias Moroder1,2, Marcos Curty1, and Norbert Lütkenhaus1,2

  • 1Institute of Theoretical Physics I and Max-Planck Research Group, Institute of Optics, Information and Photonics, University Erlangen-Nuremberg, Staudtstrasse 7, 91058 Erlangen, Germany
  • 2Institute for Quantum Computing, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1

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Issue

Vol. 74, Iss. 5 — November 2006

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