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Q: Fachverband Quantenoptik und Photonik
Q 47: Quanteninformation (Quantenkommunikation)
Q 47.6: Talk
Wednesday, March 21, 2007, 17:45–18:00, 5L
Quantum key distribution over 144 km — •Martin Fürst1, Henning Weier1, Tobias Schmitt-Manderbach2, Sebastian Schreiner1, Christian Kurtsiefer3, and Harald Weinfurter1,2 — 1LMU München, Schellingstr 4/III, 80799 München — 2Max Planck Institut für Quantenoptik, Hans-Kopfermann-Str. 1, 85748 Garching — 3National University of Singapore, 2, Science Drive 3, Singapore 117542
Quantum mechanics ensures the possibility of secure exchange of information between two parties. Several implementations of free space quantum key distribution (QKD) systems exist achieving distances on the order of ten kilometres. QKD on a global scale could be accomplished by free space systems connecting satellites and ground stations. As first steps towards this goal we performed an experiment over a distance of 144 km on the Canary Islands. The transmitter unit including a 15 cm diameter telescope was located on mount Roque de los Muchachos on La Palma. On Tenerife the Optical Ground Station (OGS), developed for optical communication to and from satellites, was used as the receiving telescope. Thanks to an actively controlled bidirectional tracking system the transmission loss of the link was stable with an attenuation between 25 dB and 35 dB over the whole night. We implemented the decoy state QKD protocol to establish a secure key at a rate of 40 bits/s. As this attenuation is also expected for downlinks from low earth orbit (LEO) satellites to ground stations, our experiment thus demonstrates the feasibility for space-based secure communication across the globe.