In the world of quantum technologies, few projects are grabbing as many headlines as the work being carried out by a group of physicists from the University of Science and Technology of China.
In August of 2016, they launched the first quantum satellite. Named Micius, after the ancient philosopher from the 5th century BC, the satellite recently completed its first successful operations.
In an experiment that is heralded as the first step towards secure quantum communications, the team successfully distributed entangled photons between the satellite and terrestrial base stations over 1,200km apart.
This is a record distance for entanglement (what Einstein referred to as “spooky action at a distance”). Although, in theory, entanglement should be able to take place across vast distances, in practice it has been difficult to maintain entanglement without disruption.
By utilising a satellite in orbit around the planet, rather than terrestrial networks, the Chinese have managed to avoid the interference associated with traditional networks that has limited historic attempts to maintain entanglement to distances of just 300km.
As pioneers in the field of quantum technologies, IDQ is often sought out for its opinion. In a series of articles published in the wake of The Original Science Article, CEO Gregoire Ribordy provides some context to the recent experiment.
In an article in the Verge, Gregoire explains how a reliable satellite link could be used to connect existing fiber networks into a single, global quantum network. “This proves the feasibility of quantum communications from space…The vision is that you have regional quantum key distribution networks over fiber, which can connect to each other through the satellite”.
The principle of entanglement is essential to the creation of secure quantum communications. Put simply, two photons that are entangled become “bound together” and exhibit correlated characteristics, even if separated physically by thousands of kilometres.
Anything that happens to one photon, happens to the other. The delicate nature of this relationship is what ensures secure communication, as any attempt to intercept or “eavesdrop” will disrupt the signal.
“This proves the feasibility of quantum communications from space… The vision is that you have regional quantum key distribution networks over fibre, which can connect to each other through the satellite.”
The experiment has generated a lot of interest from within the scientific community and beyond. In a recent Pentagon report by cyber-security expert John Costello, the Chinese experiments were described as “a notable advance in cryptography research”.
According to Anton Zeilinger from the University of Vienna, the experiment had “exceeded expectations” and Artur Ekert, Professor of Quantum Physics at Oxford University noted “the Chinese experiment is quite a remarkable technological achievement”
In an article for the Wall Street Journal, Gregoire Ribordy adds some context to the results of the experiment, explaining that the process described by the Chinese researchers is currently “too slow and complex to be used for practical quantum communications”.
However, he can see the practical applications in the future, adding that, using similar technologies: “China will be able to connect its embassies and other government facilities around the world”. Something that he predicts will happen within the next five years.
Lu Chaoyang, one of the project physicists, explained that the team was looking at ways to speed up the process; but was upbeat about the progress they had already made. “We have achieved a two-photon entanglement distribution efficiency a trillion times more efficient than using the best telecommunications fibers” he said. “We have done something that was absolutely impossible using conventional approaches”.