Effect of atmospheric discharges on the cryptographic key generation rate in quantum communication systems
O. S. Belova, D. V. Bolotov, Evelin Y. Bushuev, S. E. Grychkin, Sergey Yu. Kazantsev, T. V. Kazieva, O. V. Kolesnikov, E. P. Stroganova · Journal of Optical Technology · 2025
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.