Free-space quantum key distribution over 144 km
M. Fürst, H. Weier, T. Schmitt-Manderbach, Rupert Ursin, Felix Tiefenbacher, T. Scheidl, Michael Lindenthal, B. Blauensteiner, Thomas D. Jennewein, Pavel Trojek, J. Perdigués, Zoran Sodnik, C. Barbieri, John Rarity, Anton Zeilinger, Harald Weinfurter · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2006
We report on the experimental implementation of a BB84-type quantum key distribution protocol over a 144 km free-space link using weak coherent laser pulses. The security was assured by employing decoy state analysis, and optimization of the link transmission was achieved with bi-directional active telescope tracking. This enabled us to distribute a secure key at a rate of 11 bits/s at an attenuation of about 35 dB. Utilizing a simple transmitter setup and an optical ground station capable of tracking spacecraft in low earth orbit, this outdoor experiment demonstrates the feasibility of global key distribution via satellites.