Russia and China conducted an experiment on transmitting messages protected using quantum cryptography. A Russian ground station in Zvenigorod exchanged encoded images of 256×64 pixels with a ground station in Nanshan, China, via the Chinese quantum communication satellite "Mo-tzu."
China has been operating its own quantum network with a length of 4600 km for many years, which is used by banks and companies. To solve the problem of quantum communications between different continents, Chinese scientists began conducting research with the participation of "Mo-tzu" in 2016. In 2019, Russians from NUST MISIS, RQC, and "KuSpace Technologies" joined them. During a series of experiments, it was possible to implement quantum key distribution between two points at a distance of 3800 km: between ground stations in Zvenigorod and Nanshan.
What is quantum cryptography for?
Quantum cryptography and quantum satellite communication are ways to protect information in the digital world from leaks and a response to the growing computing power of malicious actors. Quantum computers in the hands of hackers can easily cope with the mathematical algorithms on which traditional cryptography is based to protect information. In the case of quantum cryptography, it is based on physics: information is encoded in single quanta, it is impossible to read it imperceptibly, which makes it possible to transmit cryptographic keys.
However, the optical signal in the fiber through which photons are transmitted weakens, and the data transmission infrastructure requires intermediate trusted nodes. Therefore, the transmission of cryptographic keys via satellite seems optimal.
The method of distributing quantum keys via fiber optics has limitations: the flow of light particles loses its energy, being absorbed in the fiber, and after a couple of hundred kilometers, the signal becomes so weak that it cannot be distinguished from noise. It is worth noting that such a quantum signal cannot be silently amplified during distribution. In this context, the transmission of keys via satellite in open space, where there is nothing that could significantly absorb or scatter light, represents a significant advantage and allows keys to be transmitted to any point on earth more efficiently than via fiber optics.
The receiving ground station in Zvenigorod can conduct stable communication sessions with the satellite and decode the polarization states of single photons sent by the spacecraft.
Where is quantum cryptography used?
According to various estimates, the quantum cryptography market in the world will grow by an average of almost 40% per year. In global practice, large banks and telecommunications companies are already using or testing this technology - as, for example, China is doing. In Russia, Rosatom and Rostelecom were the first to launch a pilot project in this direction, and the quantum communications infrastructure is being built with the support of the Russian Railways Roadmap. There is also at least one private company that is engaged in this technology - "QuRate", founded with the support of the Russian Quantum Center.
Satellite quantum cryptography can be used in Russia to protect data of objects located at a great distance. In particular, between remote mineral deposits or for communication between icebreakers. As part of the strategic project of NUST MISIS "Quantum Internet" under the Ministry of Education and Science of Russia program "Priority 2030", researchers have already studied the risks for attacker attacks with this method of communication and eliminated them. This is an important step towards creating high-speed quantum-protected satellite communication systems in Russia.
Does Russia have its own quantum satellites?
They will appear soon. In the summer of 2023, the first Russian prototype of a quantum satellite was launched from the Vostochny cosmodrome: the small spacecraft "Impulse-1" from NUST MISIS and "KuSpace Technologies". It contains equipment that allows testing the transmission of information via a laser communication channel. Communication sessions with it are proceeding as normal. According to MISIS, "big business has already begun to show interest in this area, and the development of quantum microsatellite technology is bringing closer the horizon of economic feasibility of introducing quantum technologies".