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 language | English |
---|---|
Pages (from-to) | 202-209 |
Number of pages | 8 |
Journal | Optics Express |
Volume | 13 |
Issue number | 1 |
DOIs | |
Publication status | Published - 10 Jan 2005 |
Keywords
- KEY DISTRIBUTION
- OPTICAL COMMUNICATION
- CRYPTOGRAPHY
- DAYLIGHT
- VIOLATION
- PAIRS
- TELEPORTATION
- INEQUALITY
- EXCHANGE