New Journal of Physics (Jan 2014)

A fast and versatile quantum key distribution system with hardware key distillation and wavelength multiplexing

  • N Walenta,
  • A Burg,
  • D Caselunghe,
  • J Constantin,
  • N Gisin,
  • O Guinnard,
  • R Houlmann,
  • P Junod,
  • B Korzh,
  • N Kulesza,
  • M Legré,
  • C W Lim,
  • T Lunghi,
  • L Monat,
  • C Portmann,
  • M Soucarros,
  • R T Thew,
  • P Trinkler,
  • G Trolliet,
  • F Vannel,
  • H Zbinden

DOI
https://doi.org/10.1088/1367-2630/16/1/013047
Journal volume & issue
Vol. 16, no. 1
p. 013047

Abstract

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We present a compactly integrated, 625 MHz clocked coherent one-way quantum key distribution system which continuously distributes secret keys over an optical fibre link. To support high secret key rates, we implemented a fast hardware key distillation engine which allows for key distillation rates up to 4 Mbps in real time. The system employs wavelength multiplexing in order to run over only a single optical fibre. Using fast gated InGaAs single photon detectors, we reliably distribute secret keys with a rate above 21 kbps over 25 km of optical fibre. We optimized the system considering a security analysis that respects finite-key-size effects, authentication costs and system errors for a security parameter of ε _QKD = 4 × 10 ^−9 .