MIPT, MISIS and RCC: A semi-empirical model of quantum key distribution between a satellite and a ground station

Main article:

• Quantum Computers and Quantum Communications
• Quantum cryptography (encryption)

2023: Matmodel to quickly assess the effectiveness of satellite quantum communications

Scientists from MIPT, MISIS University and the Russian Quantum Center have obtained a mathematical model to quickly assess the effectiveness of satellite-quant communication. This was reported to TAdviser on May 2, 2023 by representatives of MISIS University. According to the researchers, calculations based on the proposed model for the distribution of keys from the Mo-Tzu satellite to the ground station created in Russia will simplify and speed up the practical modeling of the quantum communication channel.

Russian scientists have created a mathematical model to improve the quality of satellite quantum communications

Traditional cryptography public key enciphering is based on the computational complexity of certain mathematical functions. Quantum Key Distribution Technology (KRK) allows you to organize an absolutely secure communication channel, where the information resistance of the encryption key is guaranteed by the laws of quantum physics, scientists said.

According to them, the KRK has a number of advantages. First, such a key cannot be cracked after the quantum key distribution procedure. This means that enciphering it is resistant to the attacks computer to any capacity in the future, including. quantum computer Secondly, by the number of errors in the key, it is possible to detect an interception attack and stop the communication session in time without leaks any information.

Long-distance satellite quantum communications have a significant advantage over fiber links in terms of link loss. This is becoming a determining factor for quantum communications on a planet scale, the researchers emphasized.

Quantum key distribution between two subscribers usually occurs using photons that are transmitted through optical fibers or in free atmospheric space. Fiber is limited to a space of hundreds of kilometers, we cannot stretch it through the oceans, unlike orbital satellites, which are able to cover the entire surface of the planet, with minimal loss of signal quality at the same time, - explained at MISIS University.

Meanwhile, the analysis of the communication channel between the satellite and the ground station is very important for effective satellite quantum communication. According to MISIS, this is especially critical for low-orbit satellites: due to the short time the satellite is in line of sight of the ground station for signal transmission and dependence on weather conditions.

Matmodel developers Alexander Khmelev and Vladimir Kurochkin

A team of scientists from MIPT, MISIS University and the Russian Quantum Center has proposed a semi-empirical model of quantum key distribution (KRK) between a satellite and a ground station. It will allow you to quickly assess the effectiveness of already designed ground stations and will serve to develop and analyze the constellation of satellites for quantum key distribution.

"Unlike other purely theoretical models, our semi-empirical approach is based on atmospheric attenuation coefficients common to ground stations that are located at mid-latitudes. These coefficients characterizing the atmosphere in terms of permeability to light were obtained experimentally both for clear and foggy weather conditions using a developed ground station, "said Alexander Khmelev, a graduate student at LFI MIPT, a researcher at the RCC. - Verification of the model and phenomenological parameters was carried out using published experimental data from the Mo-Tzu satellite. Using our model for real ground stations based on telescopes with an aperture of 300 mm and 600 mm, we simulated the rate of generation of the secret key obtained during the CRK session with the Mo-Tzu satellite. "

The atmospheric attenuation coefficient was obtained from measurements of the radiation intensity of stars at a wavelength of 850 nm for both clear and foggy skies. They were carried out using developed ground stations based on a 600 mm telescope in photon counting mode, the authors noted.

"We are working on the possibility of a global distribution of the quantum key over the entire surface of the globe using satellites with optical quantum communication channels. Ground receiving stations for this type of communications have already been developed, "said Vladimir Kurochkin, head of the quantum communications laboratory at MISIS University. - To create satellites with a quantum communication line, it is important to be able to correctly calculate the parameters of the satellite, the receiving ground station and the data transmission rate. The proposed quantum communication channel model will predict the rate of key distribution. This will help in the creation of our satellite in the future. "

Thus, the researchers developed a practical method for evaluating the efficiency of ground stations, which are one of the key elements of future quantum networks. The developed model will be useful for rapid assessment of satellite communication channels and analysis of future quantum systems "Sputnik-Earth," concluded in MISIS. The results of the work of Russian scientists are presented in the international scientific journal Entropy.