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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 16, Iss. 21 — Oct. 13, 2008
  • pp: 16840–16853

Entangled quantum key distribution over two free-space optical links

C. Erven, C. Couteau, R. Laflamme, and G. Weihs  »View Author Affiliations

Optics Express, Vol. 16, Issue 21, pp. 16840-16853 (2008)

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We report on the first real-time implementation of a quantum key distribution (QKD) system using entangled photon pairs that are sent over two free-space optical telescope links. The entangled photon pairs are produced with a type-II spontaneous parametric down-conversion source placed in a central, potentially untrusted, location. The two free-space links cover a distance of 435 m and 1,325 m respectively, producing a total separation of 1,575 m. The system relies on passive polarization analysis units, GPS timing receivers for synchronization, and custom written software to perform the complete QKD protocol including error correction and privacy amplification. Over 6.5 hours during the night, we observed an average raw key generation rate of 565 bits/s, an average quantum bit error rate (QBER) of 4.92%, and an average secure key generation rate of 85 bits/s.

© 2008 Optical Society of America

OCIS Codes
(060.4510) Fiber optics and optical communications : Optical communications
(270.0270) Quantum optics : Quantum optics
(200.2605) Optics in computing : Free-space optical communication
(270.5565) Quantum optics : Quantum communications
(270.5568) Quantum optics : Quantum cryptography

ToC Category:
Quantum Optics

Original Manuscript: July 15, 2008
Revised Manuscript: September 15, 2008
Manuscript Accepted: September 30, 2008
Published: October 7, 2008

C. Erven, C. Couteau, R. Laflamme, and G. Weihs, "Entangled quantum key distribution over two free-space optical links," Opt. Express 16, 16840-16853 (2008)

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