Long-Distance Quantum Cryptography with Entangled Photons

Author(s): A. Zeilinger

Journal: Proc. SPIE

Volume: 6780

Page(s): 67800B

Year: 2007

DOI Number: 10.1117/12.740268

Link: Link to publication


Entanglement-based quantum cryptography has the appealing advantage of intuitively more evident security. While originally, weak laser pulse schemes were implemented earlier as technologically simpler, it is now possible to build

entanglement-based quantum key distribution systems on a technically equally advanced level. The existing polarizationbased systems as developed in Vienna now cover distances of the order of 100 km in fiber and of 144 km in free space.

In a recent fiber experiment, an asymmetric source is used such that one photon at the 1.550 nm telecom wavelength is transmitted to Bob, while the other photon at 810 nm is locally measured by Alice. It turns out that polarization

entanglement is rather robust, certainly over distances of 100 km in fibers. In a recent long-distance free-space experiment, one photon was sent over 144 km from the Canary Island of La Palma to the island of Tenerife, while again

the other photon was measured locally. The receiving station uses the OGS telescope operated by the European Space Agency ESA. This experiment opens up the possibility for future quantum key distribution using satellites.

Note: From Conference Volume 6780 Quantum Communications RealizedYasuhiko Arakawa; Masahide Sasaki; Hideyuki SotobayashiBoston, MA | September 09, 2007

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