Key parameters of single photon receivers and sources for fi ber-optic quantum cryptography systems: parameter analysis and measurement methods

The development of fi ber-optic communication and data transmission systems gives rise to a number of new challenges, among which information protection against unauthorized access is of particular relevance. In response to this need, quantum cryptography has emerged – optical cryptographic systems with quantum key distribution. Such systems protect communication channels by encrypting data with a one-time secret key. The theoretical foundation guaranteeing secure key transmission relies on the Heisenberg uncertainty principle and the no-cloning theorem for quantum states of elementary particles. However, real-world quantum cryptography systems exhibit vulnerabilities stemming from imperfections in their components. Single photon detectors and single photon sources are critical elements of quantum key distribution systems. This work analyses the main types of attacks on quantum cryptography equipment and identifi es the key parameters of single photon sources and single photon detectors.

Knowledge of their actual values can be crucial for proving a system’s resilience against attacks. Additionally, the paper describes the equipment and methods used to study single-photon sources. The study also describes the method and results of investigating the quantum effi ciency and false trigger probabilities of gated single-photon detectors with fi ber input. The described measurement methods are harmonized with the recommendations of the European Telecommunications Standards Institute. Together, the described measurement techniques and setups enable the assessment of single photon source and detector parameters during expert evaluation of quantum cryptography system vulnerabilities. The paper concludes with a call for the establishment of a reference database to support metrological assurance of key parameters for single photon sources and receivers, in order to advance quantum cryptography systems

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