Hamburg 2009 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 48: Quanteninformation: Quantenkommunikation I
Q 48.3: Talk
Thursday, March 5, 2009, 14:30–14:45, Audi-B
Daylight free space quantum cryptography — •Harald Krauss1, Martin Fürst1,3, Sebastian Schreiner1, Henning Weier1,3, Markus Rau1, and Harald Weinfurter1,2 — 1Department für Physik der LMU München, Schellingstr. 4/III, 80799 München — 2Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str. 1, 85748 Garching — 3quTools GmbH, Königinstr. 11a, 80539 München
The BB84 quantum key distribution (QKD) scheme allows provably secure communication. We report on our free space implementation of the BB84 protocol linking two Siemens buildings downtown Vienna in the framework of a QKD network demonstration (SECOQC). The setup uses polarization encoded attenuated laser pulses in combination with decoy states to ensure secret key generation over a distance of 80 m. For the first time continuous and fast daylight operation could be achieved. Employing an active automatic position tracking system and improved filtering methods, key distribution rendered possible even during bad weather conditions. Our system is fully remotely controllable and integrates into SECOQC's network which provides the interface for secure communication in common network applications. The experiments prove daylight free space QKD to be feasible. High secure keyrates of already 20 kbit/s were achieved on a 24/7 basis, while the setup still stays both robust and simple, allowing for everyday applications.