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Optics Express

Optics Express

  • Editor: Michael Duncan
  • Vol. 13, Iss. 1 — Jan. 10, 2005
  • pp: 202–209

Distributing entanglement and single photons through an intra-city, free-space quantum channel

K.J. Resch, M. Lindenthal, B. Blauensteiner, H.R. Böhm, A. Fedrizzi, C. Kurtsiefer, A. Poppe, T. Schmitt-Manderbach, M. Taraba, R. Ursin, P. Walther, H. Weier, H. Weinfurter, and A. Zeilinger  »View Author Affiliations

Optics Express, Vol. 13, Issue 1, pp. 202-209 (2005)

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We have distributed entangled photons directly through the atmosphere to a receiver station 7.8 km away over the city of Vienna, Austria at night. Detection of one photon from our entangled pairs constitutes a triggered single photon source from the sender. With no direct time-stable connection, the two stations found coincidence counts in the detection events by calculating the cross-correlation of locally-recorded time stamps shared over a public internet channel. For this experiment, our quantum channel was maintained for a total of 40 minutes during which time a coincidence lock found approximately 60000 coincident detection events. The polarization correlations in those events yielded a Bell parameter, S=2.27±0.019, which violates the CHSH-Bell inequality by 14 standard deviations. This result is promising for entanglement-based free-space quantum communication in high-density urban areas. It is also encouraging for optical quantum communication between ground stations and satellites since the length of our free-space link exceeds the atmospheric equivalent.

© 2005 Optical Society of America

OCIS Codes
(060.4510) Fiber optics and optical communications : Optical communications
(270.0270) Quantum optics : Quantum optics

ToC Category:
Research Papers

Original Manuscript: December 8, 2004
Revised Manuscript: December 23, 2004
Manuscript Accepted: December 28, 2004
Published: January 10, 2005

K.J. Resch, M. Lindenthal, B. Blauensteiner, H.R. Böhm, A. Fedrizzi, C. Kurtsiefer, A. Poppe, T. Schmitt-Manderbach, M. Taraba, R. Ursin, P. Walther, H. Weier, H. Weinfurter, and A. Zeilinger, "Distributing entanglement and single photons through an intra-city, free-space quantum channel," Opt. Express 13, 202-209 (2005)

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