Applicability of quantum key distribution technology under free-space atmospheric conditions to construct segments of modern quantum communication networks
Kirill Yu. Erokhin, Sergey Yu. Kazantsev, T. V. Kazieva, Yu. B. Mironov, Natalia V. Pchelkina
Subject of study. This study examined the applicability of quantum key distribution (QKD) technology under free-space atmospheric conditions. Aim of study. The objective was the development of a hardware and software system for investigating the applicability of QKD technology in wireless communication systems based on commercially available modules. The system includes optical blocks for atmospheric optical communication and a training setup for studying QKD in fiber-optic communication lines. Method. The characteristics of a quantum communication channel in free-space conditions were studied through experiments. The channel was formed by the QKD units of the EMQOS 1.0 scientific and educational complex, integrated with optical blocks for atmospheric optical communication. The systems were also upgraded to minimize losses in the quantum channel. Main results. A hardware and software system was developed, within which the transmission of a quantum key through free-space atmospheric conditions over a distance of 180 m was successfully demonstrated. The quantum bit error rate did not exceed 6%. This system enabled the study of the effects of weather conditions on optical losses in the quantum communication channel and the quantum key generation rate. Practical significance. The developed hardware and software system allows the monitoring of the parameters of both classical and quantum communication channels in free space under various weather conditions. Its modular structure enables the integration of other quantum equipment for comparative testing of the performance of quantum communication systems under real atmospheric transmission conditions.
Subject of study. This study examined the applicability of quantum key distribution (QKD) technology under free-space atmospheric conditions. Aim of study. The objective was the development of a hardware and software system for investigating the applicability of QKD technology in wireless communication systems based on commercially available modules. The system includes optical blocks for atmospheric optical communication and a training setup for studying QKD in fiber-optic communication lines. Method. The characteristics of a quantum communication channel in free-space conditions were studied through experiments. The channel was formed by the QKD units of the EMQOS 1.0 scientific and educational complex, integrated with optical blocks for atmospheric optical communication. The systems were also upgraded to minimize losses in the quantum channel. Main results. A hardware and software system was developed, within which the transmission of a quantum key through free-space atmospheric conditions over a distance of 180 m was successfully demonstrated. The quantum bit error rate did not exceed 6%. This system enabled the study of the effects of weather conditions on optical losses in the quantum communication channel and the quantum key generation rate. Practical significance. The developed hardware and software system allows the monitoring of the parameters of both classical and quantum communication channels in free space under various weather conditions. Its modular structure enables the integration of other quantum equipment for comparative testing of the performance of quantum communication systems under real atmospheric transmission conditions.
This paper presents a comprehensive analysis of the application of quantum key distribution technology in atmospheric optical communication lines to ensure the information security of transmitted information in urban infrastructure conditions and between critical infrastructure industrial facilities. The necessity of applying quantum key distribution technology in atmospheric optical communication channels is substantiated. The results of numerical modeling of quantum key distribution performance indicators confirm the need for their preliminary numerical analysis taking into account regional meteorological statistical data when designing network segments including atmospheric quantum key distribution systems. The developed software package enables optimization of system parameters for specific climatic conditions and channel topology which increases the efficiency of deploying secure networks including atmospheric optical channels for energy, financial and industrial facilities. The developed software package, implementing a physically based methodology for accounting for cumulative losses in such a communication channel, enables a comprehensive assessment of the effectiveness of quantum key distribution taking into account turbulence, absorption, scattering, geometric losses, meteorological conditions and the characteristics of the detection equipment. The practical significance of the complex lies in the ability to optimize system parameters (wavelength, aperture diameter, transmitter power, etc.) for specific climatic conditions and channel topology, which is critical when designing secure networks that include atmospheric optical channels.
Subject of study. An optical system, composed of transmitting and receiving telescopes, was designed for quantum key distribution, based on the subcarrier wave modulation method, over an atmospheric channel. Aim of study. The aim of the study was to develop an optical system that allowed the use of single-mode fibers as the input and output of the system, ensured the transmission of an ultralow-power optical signal without introducing additional distortion, and implemented a protocol for distributing a quantum key over an atmospheric optical communication channel at a distance of up to 25 m. Method. An experimental setup with an atmospheric quantum communication channel was developed, which showed stable quantum key distribution without interruptions throughout the measurement process. Radiation propagation simulations were also performed to estimate the insertion loss of the optical signal. Main results. Simulations revealed that the optical losses in the quantum key distribution system amounted to approximately 17 dB. The atmospheric communication channel was studied at distances of 5, 10, and 25 m. Considering all optical elements of the system, including the ferrules of the output and input fibers of the quantum key distribution modules, the attenuation of the optical signal was approximately 8, 13, and 18 dB, respectively. Based on the atmospheric optical losses, the quantum key generation rates were of the order of 500, 350, and 190 bits/s with increasing distance and insertion losses. The probability of a quantum error was in the range of 3% to 5%, which was lower than the threshold of 6%, ensuring the legitimacy of the generated key and excluding the possibility of an attack on the communication channel. Practical significance. The compatibility of the developed optical system with single-mode optical fibers allows its integration into the existing infrastructure of data transmission lines without the need for additional optical radiation converters. Owing to the analyzed characteristics of the optical system for distributing a quantum key over an atmospheric communication channel, it can be applied in communication systems based on the Internet of Things, unmanned vehicles, and other moving objects.
The article analyzes the main trends in the field of optimization of information transmission processes using quantum methods. It is shown that numerical modeling of satellite optical communication systems is necessary in order to determine the most effective modes and parameters of communication equipment. This article is devoted to the problem of developing a software package for calculating the characteristics of a communication channel between a ground station and an artificial Earth satellite. A detailed description of the basic functions of the developed software package for calculating the characteristics of an Earth-satellite optical communication channel protected by QKD technology is presented. Based on numerical modeling using the developed software package, a comprehensive study of the influence of atmospheric losses, as well as various parameters of the receiving and transmitting equipment of both the ground station and the satellite, is carried out. In particular, when modeling the efficiency of satellite quantum key distribution and an optical communication channel, atmospheric phenomena such as refraction, absorption, aerosol scattering, as well as the parameters of the QKD equipment were taken into account. Modeling revealed the need to take into account many aspects to achieve maximum efficiency of the QKD in real conditions. It is shown that the developed software for flexible modeling of various scenarios for using atmospheric optical communications opens up new opportunities for research and practical application of quantum technologies in the field of information security, which is important for data protection in the face of growing cybersecurity threats. It is shown that the capabilities of the developed software package can contribute to the creation of standardized approaches to assessing and improving quantum key distribution systems.
The possibility of implementing the technology of quantum key distribution on discrete variables in free space is demonstrated. The experimental setup is based on mass produced equipment – terminals for atmospheric optical communication lines and the scientific and educational complex EMQOS 1.0. The latter is designed for conducting educational and research work in the field of quantum optics. The nodes that need to be modified in equipment have been identified. Both terminals for atmospheric optical communication lines and quantum key distribution units were modified accordingly in order to implement the modular principle of building quantum communication systems in the atmosphere.
Subject of study. Technology for quantum key distribution in fiber-optic communication lines under the influence of electromagnetic fields generated by atmospheric discharges is studied. Aim of study. A test bench for testing experimental techniques to be used in studying the effect of atmospheric discharges on transmission of a quantum key via fiber-optic communication lines is developed. Method. The characteristics of a quantum communication channel upon exposure of a coil containing an optical fiber to a magnetic field from a pulsed current are experimentally studied. Main results. An experimental test bench has been created and methods have been developed to evaluate the influence of magnetic fields arising from atmospheric discharges (lightning) on the transmission speed of a quantum key in fiber-optic communication lines. It was shown that quantum key distribution blocks using the BB84 phase-encoding protocol continue to show operational stability when the optical cable is exposed to alternating magnetic fields of up to 1.2 mT. However, the very fact of exposure to magnetic fields above 0.8 mT can be detected by a systematic decrease in the quantum key transmission rate and an increase in the quantum bit error rate (QBER) by 0.5%–1%. Practical significance. The laboratory test bench and methods developed herein support magnetic-field testing of various optical cables used for transmission of qubits. Fiber-optic networks through which qubits are transmitted can serve as a distributed lightning sensor; an increase in the level of quantum errors and a decrease in quantum key generation rate will be observed in any segment of an optical network where a lightning discharge generates strong magnetic fields.
Abstract The establishment of a world-wide quantum communication network relies on the synergistic integration of satellite-based links and fiber-based networks. The first are helpful for long-distance communication, as the photon losses introduced by the optical fibers are too detrimental for lengths greater than about 200 km. This work aims at giving, on the one hand, a comprehensive and fundamental model for the losses suffered by the quantum signals during the propagation along an atmospheric free-space link. On the other hand, a performance analysis of different quantum key distribution (QKD) implementations is performed, including finite-key effects, focusing on different interesting practical scenarios. The specific approach that we chose allows to precisely model the contribution due to different weather conditions, paving the way towards more accurate feasibility studies of satellite-based QKD missions.