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.
©2005 Optical Society of America
Full Article | PDF ArticleMore Like This
C. Erven, C. Couteau, R. Laflamme, and G. Weihs
Opt. Express 16(21) 16840-16853 (2008)
Xiao-song Ma, Sebastian Kropatschek, William Naylor, Thomas Scheidl, Johannes Kofler, Thomas Herbst, Anton Zeilinger, and Rupert Ursin
Opt. Express 20(21) 23126-23137 (2012)
Emma Brambila, Rodrigo Gómez, Riza Fazili, Markus Gräfe, and Fabian Steinlechner
Opt. Express 31(10) 16107-16117 (2023)