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A “secure quantum link” has just been established between two Chinese cities more than 500 km apart, without the need for intermediate coding. Approaching the development of a quantum web

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A new step forward in the development of network quantum internet from the future. Those that, at least in theory, should guarantee us ultra-secure connections, ultra-fast connections, even more precise time synchronization: a real revolution, which promises to fundamentally change the way we exchange information. Today’s news is that a team of Chinese scientists has managed to create one secure sleeve connection Between two Chinese cities separated by a distance of 511 kilometers without the need for an encrypted intermediary between them. The details were Published in the magazine Nature Photonics.

The basic concept of quantum web development lies in the phenomenon فيtangleOh quantitative correlation, according to which two or more (quantum) particles are intrinsically related to each other in such a way that every measurement made on one is immediately reflected on the other or on the others. Imagine, for example, that we have two quantum-correlated photons: by measuring the state of one, it is possible to infer (and modify) the state of the other as well, regardless of their distance. This mechanism, among other things, underlies Quantum cipherParticles entangled can be used to create secret keys through which information can be decoded, ensuring that any unjustified attempt to access or tamper with sensitive data will lead to its irreparable destruction.

In previous studies, scientists have shown how a pair of photons can be formed entangled and transmit one of the two to a receiver, effectively creating a link based on a quantum key. In today’s experience, the team Chiang Chang, subordinate University of Science and Technology of China, he extended the maximum distance of such a link using a cable and an intermediate point that does not read the data, but only checks its integrity at the time of transmission. It works like this: at the ends of the fiber-optic cable there are laser beams that send two beams of photons against each other. When there are two photons of the two rays in stage (for example, simplifying, when the peaks of the relative light waves are aligned) and meet at the intermediate point, this “Warn” The transmitter, receiver, and signals are identical, and these signals exchange a quantum key: in this way,center Central does not know the content of the message, but only if and when the two signals match.

A recent experiment in Cambridge, UK, has already managed to show that this system works at a distance of more than 600 km, but in this case it all happened in the lab; But this time the contact occurred at a distance of 511 km RealityBetween the cities of Jinan and Qingdao, as the authors of the work proudly point out: “In the lab you have a controlled environment, with an air conditioner that keeps the temperature stable. It’s more difficult in the real world, because the phase of the photons can change as the temperature changes”. The goal now is to cross the 1,000 kilometres. Who knows who will succeed first.