Phys.org  October 10, 2023
An international team of researchers (Germany, Austria) developed a deployable free-space QKD system and demonstrated its use in realistic scenarios. They developed and launched a low-Earth-orbit satellite for implementing decoy-state QKD—a form of QKD that uses weak coherent pulses at high channel loss and was secure because photon-number-splitting eavesdropping could be detected. They achieved a kilohertz key rate from the satellite to the ground over up to 1,200 kilometres. The key rate was around 20 orders of magnitudes greater than that expected using an optical fibre of the same length. According to the researchers their work could move forward the establishment of a reliable and efficient space-to-ground link for quantum-state transmission at global-scale quantum networks… read more. Open Access TECHNICAL ARTICLE  1 , TECHNICAL ARTICLE 2Â
Metropolitan entanglement-based free-space network. Credit: npj Quantum Information volume 9, Article number: 95 (2023)