Quantum key distribution at space scale

Quantum key distribution (QKD) promises unconditionally secure communication provided by fundamental laws of quantum mechanics. Current QKD systems suffer from range limitations either due to the earth´s curvature or attenuation in optical fibers. The Chinese and Austrian Academies of Science decided to jointly establish the required technologies and infrastuctures for a satellite based global quantum key distribution network. Here we present the proposed experiment as well as the proof-of-concept demonstrations conducted on a 143 km horizontal free-space link between the Canary Islands (Spain) and a 6 km horizontal link in Graz (Austria).