In connection with volumes of the transferred information grow, the list of telecommunication services extends and at the same time increase the quality requirements. Russian operators of Uniform telecommunication network should solve the problem of increasing the throughput of existing lines. Some Russian operators have already moved to coherent detection technology in own fiber-optic transport network. However, this transition is uneconomical due to the high cost of equipment. Multilevel modulation formats include high spectral efficiency and resistance to dispersion, it is useful for increasing the transmission rate in communication systems with wavelength division multiplexing. Article presents a model of fiber-optic channel model, which allows finding the optimal location of the signal levels with multilevel modulation intensity (IM-M). The model is create according to postulates of quantum electrodynamics and has good convergence to results of known researches. This model can be a solution to many optimization problems of synthesis and analysis of fiber-optical communication lines with multilevel signals.
In connection with volumes of the transferred information grow, the list of telecommunication services extends and at the same time increase the quality requirements. Russian operators of Uniform telecommunication network should solve the problem of increasing the throughput of existing lines. Some Russian operators have already moved to coherent detection technology in own fiber-optic transport network. However, this transition is uneconomical due to the high cost of equipment. Multilevel modulation formats include high spectral efficiency and resistance to dispersion, it is useful for increasing the transmission rate in communication systems with wavelength division multiplexing. Article presents a model of fiber-optic channel model, which allows finding the optimal location of the signal levels with multilevel modulation intensity (IM-M). The model is create according to postulates of quantum electrodynamics and has good convergence to results of known researches. This model can be a solution to many optimization problems of synthesis and analysis of fiber-optical communication lines with multilevel signals.
The analysis of the performance indicators fiber-optic communication lines (FOCL) using quantum technology based on the architectural concept of NGN (Next Generation Network) and future networks FN (Future Networks) for the construction highly efficient optical telecommunication networks supporting a wide range cryptographic resistance. Threats of unauthorized access, denial of service, loss information, cryptographic methods and algorithms for information protection are considered. Complex criteria of FOCL efficiency using such quantum technologies as network performance using WDM (Wavelength Division Multiplexing) technology, information security characteristics when using quantum cryptography protocols, taking into account resistance to various threats, informative characteristics photon sources are selected. A new approach is proposed for the study and assessment of complex indicators complex optical information protection systems and effective control of a set quantum key distribution systems for fiber-optic communication lines. The functioning of the investigated FOCL using quantum technology based on the principles "Point-to-point" network topology, which allows organizing a quantum information and service channel, is considered. On the basis of the proposed approach, the efficiency quantum key distribution, the capabilities quantum cryptography protocols under the influence of photon number splitting attack (PNS-Photon Number Splitting Attack) and the information entropy of the characteristics of sources of optical photon qubit fluxes are investigated. Analytical expressions are obtained for assessing the complex indicators of the information security system when using quantum key distribution (QKD) for FOCL. On the basis of the new approach, a numerical analysis was carried out and a graphical dependence of the information entropy of the packet on the packet length in qubits was constructed for the given transfer characteristics of the FOCL. It was found that an increase in the limited packet length in bits, which meets the requirements reliability and efficiency of the operation FOCL system, leads to an increase in the value information entropy as a fraction of the packet, at a given bit rate of the network.
Already today, quantum communications networks are being actively deployed and created in Russia and around the world, and standards in the field of quantum technologies are being developed. As part of the roadmap for the development of quantum communications in Russia, the length of quantum networks is more than 7 thousand km, and by 2030 it is planned to be more than 15 thousand km. Quantum communications today are, in fact, a technology of quantum key distribution, which is at the stage of intensive scientific research and development. With regard to backbone quantum networks, the technology of secret key distribution requires new approaches to implementation, since the use of equipment from various vendors and the length of fiber-optic communication lines impose surmountable restrictions on the topology of backbone networks. An important aspect in the design of quantum networks is the calculation of losses in optical communication channels. Attenuations introduced by various passive and active elements are usually calculated individually for each section of the network and ultimately form a comprehensive energy model. The article considers several topologies of backbone quantum networks and presents the calculation of optical losses for fiber-optic communication channels of these topologies. In general, a method for detecting an optical signal in quantum communication networks is presented. The purpose of the article is a comparative analysis of energy models of backbone quantum networks and a presentation of a variant of implementing a section of an urban quantum network. The work describes a generalized principle of operation of a quantum key distribution system both in a two-pass version and in a single-pass configuration. The results of the analysis of the energy model and the calculation of average losses in a quantum channel are presented. In conclusion, we propose for consideration a possible variant of the topology of a quantum network.
Quantum cryptography is a relatively new but promising method for secure data transmission. Today it is believed that it can ensure the absolute secrecy of data, resulting from the principles of quantum physics, on which it is based, namely the uncertainty principle of quantum Heisenberg. According to this principle cannot measure any aspect of photons without distorting thus irrevocably different option. That is the recipient of a message knows when attempting invasion in this necessarily knows.To create a quantum communication channel often use fiber optic lines or open space in which carriers serve single photons or pairs of entangled photons are often used.Three tasks facing cryptography are:1. Ensuring the confidentiality of messages sent via open communication channels.2. Authentication messages that confirm the validity of the information received and sent.3. Installing intrusion in fact, if it took place.Given the importance of information security, quantum cryptography technology will soon be available not only banks or large corporations but also individuals. Leading IT companies are in search of optimum circuit solutions that would produce industrial equipment for the transmission of confidential information available for mass use. The main obstacles for implementation of quantum cryptography methods are short distances, which can transmit information with modern facilities, high cost and cumbersome equipment. To solve these problems prompted the idea of creating a hybrid air-fiber system using satellite communications is proposed. The use of artificial satellites for the transmission of photons through the air opens the possibility of secret key clients in any part of the Earth and even beyond.It is also appropriate to review the possibility of using existing telecommunication and electrical networks for the transmission of quantum keys. The ideas p presented in the paper, open new space for scientific experiments.
Solving the problem of ensuring the information security of the fiber-optics systems requires an analysis of possible methods of unauthorized access. Improving the technology of installation and operation of the fiber-optics systems not only enhances the quality and distance of information transmission over an optical cable, but also potentially expands the range of channels for possible leakage of information transmitted through it. Improving the construct of the optical fibers, the use of such technologies as wavelength division multiplexing (WDM), necessitates a complex analysis of increasing the information capacity and security of fiber-optics systems from unauthorized access. The paper compares the security of the fiber-optics systems built on the standard single mode fiber (SSMF) and dispersion shifted fiber (DSF). It is shown that, despite of the possibility of a higher information capacity, fiber-optics systems built on DSF require more careful control to avoid unauthorized access than in the case of using standard SSMF.
We numerically evaluate the wavelength division multiplexing (WDM) data transmission of coherent phase-shift keying (PSK) and quadrature amplitude modulation (QAM) signals in optical fiber communication and deep-space communication channels with conventional homodyne-based(dyne-type) detections and various quantum detection strategies. We show the quantitative gap between these detection strategies and especially in the quantum-limited region where the quantum noise seriously limits the transmission rate. For an extremely weak signal input power, there is a crucial gap between the capacity limit and the transmission rates of the WDM system with dyne-type detections. We show that this gap is filled by applying a collective square root detection (SRD) only for each channel, not necessary for quantum collective decoding among WDM channels.
The existing methods of information delivery to the strategic and tactical management of many government agencies are expensive, not always reliable and efficient. Therefore, quantum cryptographic systems (QCS) have been actively developed in recent years. However, there are problems with the use of the QCS associated with the reliability of information transfer. First, the existing fiber-optic communication channels (FOCC) are not designed to transmit single-photon signals, which leads to the complexity of their cryptographic protection. The second is insufficiently methodically developed calculation of energy losses and errors in the evaluation of the characteristics of information transfer in FOCC QCS. In article the analysis of the energy loss factors in the classical fiber-optic channel is carried out and the additive loss formula is discussed in detail. Then we consider the fiber-optic channel of quantum information transmission with the use of integrated optical devices. The additive formula of optical losses in such a channel is discussed. The features of losses in integrated optical devices are shown. The features of quantum cryptographic system of information transmission are considered. As a result, the model of FOCC QCS taking into account energy losses is presented, which allows competently in theoretical terms and visualize the passage of information through modern quantum cryptographically secure telecommunications while providing control in government structures.