Quantum communication: prospects

(c) quantum communications possible

The telegraph "killed" pigeon mail. Radio pushed the wired telegraph. Radio, of course, has not disappeared anywhere, but other data transmission technologies have appeared - wired and wireless. Generations of communication standards are changing each other very quickly: 10 years ago the mobile Internet was a luxury, and now we are waiting for the emergence of 5G. In the near future, we will need fundamentally new technologies that will surpass modern no less than wireless pigeons.

What it can be and how it will affect all mobile communications - under the cut.

Virtual reality, data exchange in a smart city using the Internet of things, obtaining information from satellites and from settlements located on other planets of the solar system, and protecting the entire stream - such tasks cannot be solved with a new communication standard.
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Quantum confusion

(c) Quantum Entanglement With The Naked Eye . In fact, we cannot see quantum confusion, but beautiful visualization helps to understand the essence of the phenomenon.

One of the main options for the evolution of communication awaiting us is the use of quantum effects. This technology will not exclude, but can complement traditional forms of communication (although it is impossible to immediately reject the idea that a network based on quantum entanglement can theoretically supplant other types of communication).

Quantum entanglement is the phenomenon of the connection of quantum characteristics. The coupling can be maintained even if the particles diverge over a long distance, since, by measuring the quantum characteristics of one of the coupled particles, we automatically recognize the characteristics of the second. The first protocol of quantum cryptography appeared in 1984. Since then, many experimental and commercial systems based on the phenomena of the quantum world have been created.


(c) Chinese Academy of Sciences

Today, quantum communication is used, for example, in the banking sector , where special security conditions are required. Id Quantique , MagiQ , Smart Quantum companies already offer ready-made cryptosystems. Quantum security technologies can be compared with nuclear weapons - this is almost absolute protection, implying, however, serious implementation costs. If, using quantum entanglement, we transmit the encryption key, then its interception will not give the attackers any valuable information - they will get just a different set of numbers at the output, because the state of the system in which the external observer interferes changes.

Until recently, it was not possible to create a global perfect encryption system - after a few tens of kilometers the transmitted signal was attenuated. There have been many attempts to increase this distance. This year, China launched the QSS ( Quantum experiments at Space Scale ) satellite, which is to implement a quantum key distribution scheme at a distance of more than 7,000 kilometers.

The satellite will generate two entangled photons and send to Earth. If all goes well, then key distribution with entangled particles will be the beginning of a quantum communication era. Dozens of such satellites could become the basis not only of the new quantum Internet on Earth, but also of quantum communication in space: for future settlements on the Moon and Mars and for long-distance space communication with satellites heading beyond the Solar System.

Quantum teleportation

Device for quantum key distribution in the laboratory, Russian Quantum Center.

With quantum teleportation, no material transfer of the object from point A to point B takes place - the transfer of “information” takes place, not of matter or energy. Teleportation is used for quantum communications, for example, to transmit secret information. We must understand that this is not information in our usual form. Simplifying the quantum teleportation model, we can say that it will allow us to generate a sequence of random numbers at both ends of the channel, that is, we can create a cipher-notepad that cannot be intercepted. In the foreseeable future, this is the only thing that can be done with quantum teleportation.

For the first time in the world photon teleportation took place in 1997. Two decades later, teleportation over fiber optic networks became possible for dozens of kilometers (in the European program in the field of quantum cryptography, the record was 144 kilometers ). Theoretically, now in the city you can build a quantum network. However, there is a significant difference between laboratory and real conditions. Fiber optic cable is subject to temperature extremes, which change the refractive index. Due to sun exposure, the photon phase may shift, which in some protocols will lead to an error.


Kazan Quantum Center , laboratory of quantum cryptography.

Experiments are conducted around the world, including in Russia. A few years ago , the first quantum communication line in the country appeared . She linked the two buildings of the ITMO University in St. Petersburg. In 2016, scientists from the Kazan Quantum Center KNRTU-KAI and ITMO University launched the country's first multi-node quantum network, achieving the generation rate of sieved quantum sequences at 117 kbit / s on a 2.5-kilometer line.

This year, the first commercial communication line appeared - the Russian Quantum Center connected the offices of Gazprombank at a distance of 30 kilometers.

In the fall of physics, the Laboratory of Quantum Optical Technologies at Moscow State University and the Advanced Research Foundation tested an automatic quantum communication system at a distance of 32 kilometers between Noginsk and Pavlovsky Posad.

Taking into account the pace of creation of projects in the field of quantum computing and data transfer, in 5-10 years (according to physicists themselves) the technology of quantum communication will finally come out of the laboratories and will become as familiar as mobile communication.

Possible disadvantages

(c) Is Quantum Communication Possible

In recent years, the issue of information security in the field of quantum communication has been increasingly discussed. Previously it was believed that using quantum cryptography, you can transfer information in such a way that it cannot be intercepted under any circumstances. It turned out that absolutely reliable systems do not exist: physicists from Sweden have demonstrated that, under certain conditions, quantum communication systems can be hacked thanks to certain features in the preparation of a quantum cipher. In addition, physicists from the University of California proposed a weak quantum measurement method, which actually violates the principle of the observer and allows us to calculate the state of a quantum system from indirect data.

However, the presence of vulnerabilities is not a reason to abandon the very idea of ​​quantum communication. The race between attackers and developers (scientists) will continue at a fundamentally new level: using equipment with high computing power. Such equipment is not for every hacker. In addition, quantum effects may allow faster data transfer . With the help of entangled photons, almost twice as much information per unit of time can be transmitted if they are additionally encoded using the polarization direction.

Quantum communication is not a panacea, but so far it remains one of the most promising areas for the development of global communications.