The great Chinese leap towards an impregnable internet

Photons were sent on two terrestrial relays in the mountains of Tibet. © DR

Chinese scientists have just established a record distance for a quantum entanglement. This is what they claim in Science dated June 16, prefiguring a quantum internet with practically impregnable features. “Spooky action at a distance.” This is how a skeptical Albert Einstein described the phenomenon of quantum entanglement, according to which pairs or groups of particles are generated or interact in ways such that the quantum state of each particle cannot be described independently of the others, even when the particles are separated by a large distance.

Even though scientists still cannot explain it, they grasped its potential in terms of communication. The Chinese team led by the physicist Jian-Wei Pan tested the phenomenon on large distances by establishing a record distance for a quantum entanglement. They used Micius, a Chinese satellite launched in August 2016 within the Quess program (Quantum experiences on the scale of space). The satellite is equipped with a system allowing it to create entangled photons, i.e. a crystal distorting light on which a laser is sent.

A pair of entangled photons was created so that, when you measured one of them, the other had an opposite polarization state. Then these two photons were separated and sent to two terrestrial relays located in Delingha and Lijiang, two Chinese towns in the mountains of Tibet, 1,200 km apart. The repeated experience proved that the photons were indeed entangled more than a thousand times, thus more than by pure chance, and on a distance that pulverizes the previous record established in 2012 by an Austrian team, 143 km proximately, between the islands of La Palma and Tenerife in the Canary Islands.

The experience described in a video by the “Science” website:

If one is bringing up the idea of a quantum internet, it is because the data that would pass through this means would be protected where, usually, it is more fragile: during transport. In fact, there is no transport, that’s why one also talks about quantum teleportation. Hackers of the future could well be dealing with the spooky action…

However, sending quantum mails to one’s friends is not for tomorrow yet. In fact, the journey of the photon is sensitive to any kind of disruption, for example, crossing a “dirty” atmosphere. This is the reason why the vacuum of space is what’s best to avoid interference on the line.

Read the article published in “Science”

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