In a boost to future secret agents and a blow to their would-be eavesdroppers, German researchers report sending the first successful quantum communications from a moving source — an airplane traveling 180 miles-per-hour — to a stationary receiver on the ground. The study was first performed in 2012 but the results were just made public over the weekend in the journal Nature Photonics.
A propeller plane equipped with a laser exchanged quantum communication keys
Specifically, researchers from three institutes in Germany used a propeller plane equipped with a laser to exchange quantum communications keys with a telescope about 90 miles away. The burgeoning field of quantum cryptography, first proposed in the 1970s, uses quantum physics in an effort to create a communications channel that can't be eavesdropped upon without the participants noticing (though some experts have argued that it still doesn't address major intrusion points). Quantum keys need to be swapped between participants in order to set up this type of secure communications channel. Other researchers previously demonstrated quantum key exchange over fiber optic cables last year and between two stationary islands in results published in January.
But because so much of modern communications, and so much sensitive messaging, takes place using fast-moving satellites, proving quantum key exchange's viability from a rapidly moving object is critical to making the technology practical. The German researchers in this study specifically outline this as a major goal of their work, noting in their paper that "our results are representative of typical communication links to satellites." Still, with their first transmissions occurring at a sluggish 145 bits per second, it will take much more refinement before the first dedicated quantum satellites go into operation. The lead researcher involved, Sebastian Nauerth of the Ludwig Maximilian University of Munich, told The Verge it would be years before the technology would be able to be used in the field.