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By harnessing quantum effects, we nowadays can use encryption that is in principle proven to withstand any conceivable attack. These fascinating quantum features have been implemented in metropolitan quantum networks around the world. In order to interconnect such networks over long distances, optical satellite communication is the method of choice.(More)
We report experimental evidence of a time-lag synchronization of spatiotemporal complexity. The experiments were performed on two unidirectionally coupled, nonlinear-optical systems of single-feedback type. Synchronization was investigated for different degrees of complexity of the spontaneous structures, which were analyzed with cross-correlation functions(More)
The measurement of quantum signals that traveled through long distances is of fundamental and technical interest. We present quantum-limited coherent measurements of optical signals, sent from a satellite in geostationary Earth orbit to an optical ground station. We bound the excess noise that the quantum states could have acquired after having propagated(More)
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