Quantum network has been operating in Los Alamos for over two years

Quantum "smartcard"

Employees of the Los Alamos National Laboratory built a prototype network for testing quantum cryptography applications. As it turned out, the experiment has been going on for more than two years .

Quantum cryptography exploits the phenomenon of quantum entanglement, which allows information to be transmitted faster than the speed of light . If at one point in space we check the spin of an entangled photon, then at any other point in space a paired photon at the same time will show the reverse spin. This effect can be used in cryptography to transmit an encryption key with guaranteed protection against eavesdropping.

The main problem of quantum cryptography so far has been the fact that it worked only in point-to-point applications. If you wanted to send a message encrypted with a quantum key, then you could send it only to a specific addressee who has exactly the same equipment for reading the spin of photons, that is, on a specific quantum channel. In addition, the maximum length of such a channel was limited to about 100 kilometers due to technical problems with the transport of photons in an entangled state.
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In a scientific article, scientists at the Los Alamos National Laboratory tell how they tried to overcome these limitations. As part of a pilot project, a network was created, which consisted of a single server for managing quantum keys and several clients. At the same time, clients did not need to transmit encrypted messages through the server, they can do it directly among themselves, without raising the protected quantum channel. Each client installs secure channels with the server only to verify the keys and the authenticity of the message, at a convenient time.



Scientists believe that this architecture scales well, so that in the future, quantum cryptography can be used throughout the Internet. Quantum cryptography has the advantage over conventional methods in high performance: computers do not need to waste time on complex mathematical calculations, all operations are carried out in optical chips at literally the speed of light.

Now scientists are working to increase the maximum distance between the client and the server from the current 100 to 1000 km.