Quantum measurements of signals from the Alphasat TDP1 laser communication terminal
Kevin Günthner, Imran Khan, Birgit Stiller, Ömer Bayraktar, Daniel Tröndle, Herwig Zech, Gerd Leuchs, Dominique Elser, C. R. Müller, Karen Saucke, Frank F. Heine, S. Seel, Peter Greulich, Björn Gütlich, Ines Richter, S. Philipp-May, Christoph W. Marquardt · 2017
Quantum optics [1] can be harnessed to implement cryptographic protocols that are verifiably immune against any conceivable attack [2]. Even quantum computers, that will break most current public keys [3, 4], cannot harm quantum encryption. Based on these intriguing quantum features, metropolitan quantum networks have been implemented around the world [5-15]. However, the long-haul link between metropolitan networks is currently missing [16]. Existing fiber infrastructure is not suitable for this purpose since classical telecom repeaters cannot relay quantum states [2]. Therefore, optical satellite-to-ground communication [17-22] lends itself to bridge intercontinental distances for quantum communication [23-40].