Quantum key distribution (QKD) uses the laws of quantum mechanics to provide security that cannot, it claimed, be broken. Polarized photons are used to provide the binary language. Any attempt to intercept the photons disturbs them. This means that any form of surveillance can immediately be recognized so that the communication can be discarded. The theory is clear, but any practical application is still in the future.
Now, however, New Scientist reports that Sebastian Nauerth at the Ludwig Maximilian University of Munich in Germany has successfully beamed quantum communication between an aircraft in flight and a ground station. Previously, quantum communication has only been achieved between two ground stations – and this new step is seen as a precursor to a more generally available satellite-based secure communications network.
The research team presented its findings at the QCrypt conference in Singapore on 12 September. The paper concludes, “Our results are comparable with links to satellites in low earth orbits (LEO) concerning the channel attenuation as well as the angular speed. This demonstration thus clearly proofs [sic] the feasibility of QKD to satellites, high altitude platforms or intercontinental planes which together will form the basis for an efficient network enabling secure communication on a global scale.”
John Rarity, an optical engineer at the University of Bristol, UK (not involved in the experiment) points out that aligning an optical beam with a satellite will be more difficult than a relatively low flying aircraft, but in the meantime, says New Scientist, suggests that “solar-powered planes, which can stay aloft for weeks at a time, could enable QKD to be used in military surveillance.”