Russian physicists have just launched the first «dual» quantum network

© Photo : Calexa Fedorov, a physicist from the Russian quantum centerRussian physicists have just launched the first «dual» quantum network© Photo : RCC

. Scientists from the Russian quantum center has launched the country’s first multi-node quantum network for data transmission which uses two method of encryption of information. The results of experiments were published in the electronic library arXiv.org.

«Methods of quantum data protection is well established in the laboratory, but when you transfer them to an existing telecommunications and cryptographic infrastructure many problems arise in particular when using a real city. We managed to successfully solve one of them use the same network two different methods of encoding information», – says Alexey Fedorov, research fellow of RCC.

The phenomenon of quantum entanglement is the basis of modern quantum technologies. This phenomenon, in particular, plays an important role in the systems of secure quantum communication – this system completely exclude the possibility of invisible «wiretapping» due to the fact that the laws of quantum mechanics prohibit «cloning» the state of the light particles. In the present system of quantum communication are being actively developed in Europe, in China, in the United States.

The first network of this kind began to appear in Russia about three years ago. The first quantum communication line was launched at the ITMO University in 2014, when scientists associated quantum channel of two buildings of the University, via the existing underground fiber optic cable. In June 2016, the Russian quantum center announced the launch of the first «urban» lines of communication between the two branches of the Bank, and in September 2016, MSU announced the connection of two points in the cities suburbs.

Now scientists of the Roman Catholic Church has created a quantum network consisting of three nodes and two quantum channels connected to each other by a «trusted follower». Quantum secure communication by itself can only be installed directly between two points, and if the network has a complex structure, the quantum network segments need to communicate with each other nodes with repeaters that use «conventional» methods of data processing.

This creates a potential «hole» in the security which the physics of the Quantum center decided, forcing each pair of nodes to communicate through an intermediary, able to receive and produce signals. For example, in a network of three nodes «subscribers, and «mediator» In, pairs A and b and b and C have their quantum keys and the channels of transmission, which they use to transfer common to all nodes of the cryptographic key. It is used for encryption of real information, transmission of which is conducted on a «normal» lines.

Both the quantum channel networks were created in areas of conventional fiber optic networks in Moscow, one of which had a length of 30 kilometers, the second – 15 kilometers. On the first of the sites data were coded using the polarization of photons, the second in their phase.

In the experiment, the rate of generation of «processed» quantum keys to the first phase amounted to 0.1 kbps, and the rate of generation of secret key suitable for encryption – 0.02 kilobits per second. In the second section, based on the phase coding method, the rate of generation of secret key was 0.1 kbps.

«That speed of key generation is sufficient to update the key in the existing encryption devices. In future experiments, the generation speed can be increased,» continued Fyodorov.

According to him, the use of two coding methods within a single network allows for the processing and encryption of existing software solutions and platforms. This saves banks and other users of quantum networks from the need to develop new products, but simply to incorporate quantum channels into the existing telecommunications infrastructure.

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