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

Kevin J. Resch, M Lindenthal, B Blauensteiner, H.R. Bohm, A Fedrizzi, C Kurtsiefer, A Poppe, T Schmitt-Manderbach, M Taraba, R Ursin, P Walther, H Weier, H Weinfurter, A Zeilinger

Research output: Contribution to journalArticle

100 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)202-209
Number of pages8
JournalOptics Express
Volume13
Issue number1
DOIs
Publication statusPublished - 10 Jan 2005

Keywords

  • KEY DISTRIBUTION
  • OPTICAL COMMUNICATION
  • CRYPTOGRAPHY
  • DAYLIGHT
  • VIOLATION
  • PAIRS
  • TELEPORTATION
  • INEQUALITY
  • EXCHANGE

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