On August 15, 2016, China sent the world’s first quantum-communications satellite to the stars. Their goal? To design a perfectly impenetrable communication system with this advanced technology. Mission accomplished in June 2017. The satellite was able to distribute simultaneously entangled photons at three different ground-based stations, separated by 1,200 km. But what are the real capabilities of a quantum satellite network?
An information impossible to intercept, decipher and, therefore, to hack? This is what Wired describes citing a study published in Science. Unlike traditional methods of secured transmission, the quantum system uses photons (a fundamental particle of the electromagnetic field) in order to transmit the encryption keys needed for decoding the information.
Even if the data contained in these photons is impossible to intercept, if someone ever succeeds, they will explode “like a soap bubble”, explains Grégoire Robordy, co-founder of a company specializing in quantum encryption, to the Wall Street Journal. This phenomenon called quantum entanglement binds two protons together, although they are separated by hundreds of kilometers. If one of the two photons is modified, the other immediately is as well. The idea is to send one of the photons while keeping the other under surveillance.
Forget the optical fiber
By “teleporting” a photon from the satellite to the station down on Earth, separated by 1,203 km, China atomized the previous record in the field, which was 100 km, writes New Scientist. If we had used optical fiber to achieve such a transmission, the recurrent loss of the signal caused by the distance would only send a single pair of photons per second. “We have multiplied that efficiency by 12”, says Jian-Wei Pan of the Hefei University of Science and Technology.
When will such a network come into being?
China hopes to successfully “launch a global quantum communications network around 2030”, said Jian-Wei Pan to Xinhua, adding that “this satellite marks a turning point in China’s role. It goes from that of a ‘follower’ in the development of traditional information technologies to that of leader, leading the future achievements of the field”.