Director at Max Planck Institute of QuantumOptics, and Chair of ExperimentalPhysics, Faculty of Physics, at Ludwig Maximilian University of Munich, GarchingGERMANY and Munich, GERMANY.
First, researchers at QinetiQ, a British-government-owned company, and Ludwig MaximilianUniversity, in Munich, Germany, exchanged keys between two alpine mountain-tops more than 23km apart, though they did so at night, when sunlight could not confuse the signal.