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Q: Quantenoptik und Photonik
Q 76: Poster Quantenkommunikation
Q 76.4: Poster
Donnerstag, 16. März 2006, 16:30–18:30, Labsaal
Free-Space QKD — •Ivan Ordavo1, Henning Weier1, Tobias Schmitt-Manderbach1, Christian Kurtsiefer1,2, and Harald Weinfurter1,3 — 1Sektion 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
Quantum information theory ensures the possibility of secure exchange of information between two parties.
A variety of real-world implementations promises the realisation of quantum-cryptography based metropolitan area networks within a few years. In this work we report on progress of our QKD test-system, a prototype for an urban link, located in downtown Munich. The apparatus consists of a transmitter and receiver unit, both sited on rooftops of two university buildings at a distance of 500 m; a free space link provides the quantum channel, while a public internet connection serves as the classical channel. A completely automated alignment procedure and data-processing software for key extraction and privacy amplification complete the setup. In our implementation, properly attenuated laser pulses are used, where raw-key bits are encoded into four photon polarisation-states. Tests with BB84 protocol were performed, leading to an average sifted-key rate of about 50kbit/s. Such a compact, stand-alone free space hardware is also an obvious prerequisite for future applications, e.g. earth-satellite global QKD system.