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Q: Fachverband Quantenoptik und Photonik
Q 48: Quanteninformation (Quantenkommunikation)
Q 48.8: Talk
Thursday, March 13, 2008, 18:15–18:30, 1B
Optical Free-Space Quantum Key Distribution — •Sebastian Schreiner1, Henning Weier1, Martin Fürst1, Tobias Schmitt-Manderbach1, Christian Kurtsiefer2, and Harald Weinfurter1,3 — 1Department für Physik der LMU München, Schellingstr 4/III, 80799 München — 2Department of Physics, National University of Singapore, 2, Science Drive 3, Singapore 117542 — 3Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str. 1, 85748 Garching
The security of quantum key distribution, (QKD) is based on physical laws rather than assumptions about computational complexity: An adversary will necessarily disturb the communication by his quantum measurement. This leads to an error rate in the generated keys which allows to calculate an upper bound on the information eavesdropped. However, real implementations will be sensitive to side-channel attacks, i.e. to information losses due to distinguishabilities in other degrees of freedom, which an adversary can measure without causing errors.
Here we report on progress of our implementation of the BB84 protocol installed on top of two university buildings in downtown Munich. Using attenuated laser pulses in combination with decoy states we can establish a key over a distance of 500~m. Our system is fully remote controlled and allows for continuous and fast QKD. Additionally it is fully characterized with respect to spectral, temporal and spatial side-channels and so can guarantee secure key exchange. Our experiments proof free-space QKD to be feasible, providing high key rates while still staying both robust and simple.