Experimental Demonstration of Free-Space Decoy-State Quantum Key Distribution over 144 km
T. Schmitt-Manderbach, H. Weier, Martin L. R. Fürst, Rupert Ursin, Felix Tiefenbacher, Thomas Scheidl, J. Perdigués, Zoran Sodnik, Christian Kurtsiefer, John Rarity, Anton Zeilinger, Harald Weinfurter · Physical Review Letters · 2007
We report on the experimental implementation of a Bennett-Brassard 1984 (BB84) protocol type quantum key distribution over a 144 km free-space link using weak coherent laser pulses. Optimization of the link transmission was achieved with bidirectional active telescope tracking, and the security was ensured by employing decoy-state analysis. This enabled us to distribute a secure key at a rate of 12.8 bit/s at an attenuation of about 35 dB. Utilizing a simple transmitter setup and an optical ground station capable of tracking a spacecraft in low earth orbit, this outdoor experiment demonstrates the feasibility of global key distribution via satellites.