Optics and Photonics  November 16, 2018 An international team of researchers (Switzerland, USA – industry) has demonstrated a quantum key distribution system with a 2.5 GHz repetition rate using a three-state time-bin protocol combined with a one-decoy approach. Taking advantage of superconducting single-photon detectors optimized for quantum key distribution and ultralow-loss fiber, they can distribute secret keys at a maximum distance of 421 km and obtain secret key rates of 6.5 bps over 405 km. The research could ultimately enable cheaper and more practical systems that are a commercially viable alternative to conventional technology…read more. TECHNICAL ARTICLE