Quantum Key Distribution
hslf - 2 years ago (last modified 2 years ago)Quantum key distribution is a secure communication method which implements a cryptographic protocol involving components of quantum mechanics. Quantum key exchange refers to several methods in quantum computing and quantum cryptography that use properties of quantum mechanics to provide a common random number to two parties. Quantum key exchange does not require a quantum computer, but quantum mechanical coherence of the transmitted signals. However, when using fiber optic technologies, the distance between the transmitter and receiver is limited, as the usual signal amplifiers cannot be used due to the required coherence. The highest distance bridged by fiber optic cable, where a quantum key was exchanged, is 184.6 km, performed in 2006. In 2017, it was possible to transmit a quantum key from a satellite to Earth (about 1200 km). This is possible because the vacuum in space hardly weakens photons and causes almost no decoherence. The last part of the Earth's atmosphere causes the greatest attenuation of the signal. Local temperature variations of the atmosphere cause variations of the refractive index and thus stochastic scattering of the light wave. In ground-to-satellite communication via light waves, a current research task is to optimize the optics of the receiving and transmitting sides and to develop robust digital signal processing algorithms.
At the EU level, there is the corresponding will to establish this extremely secure form of encryption supranationally. The EU provides a corresponding FAQ.