Subject of study. A noise parameter, such as an afterpulse effect, that occurs in indium-gallium arsenide/indium phosphide single-photon avalanche diodes when operated as part of a single-photon detector in quantum key distribution systems was investigated. The aim of this study was the analysis of indium-gallium arsenide/indium phosphide single-photon avalanche diode afterpulse effect estimation approaches for real-world quantum key distribution systems and the development of a measurement technique and model for estimating the afterpulse effect in indium-gallium arsenide/indium phosphide single-photon avalanche diodes. Method. For the experimental measurement of the afterpulse probability in indium-gallium arsenide/indium phosphide single-photon avalanche diodes, a special stand was used. All components of this stand are controlled by LabVIEW software. The developed model of afterpulse probability is based on the non-Markovian character of this effect. Main results. A measurement technique and probabilistic model were developed to estimate the afterpulse based on the recursive nature of this effect in indium-gallium arsenide/indium phosphide single-photon avalanche diodes. This makes it possible to estimate the true value of the afterpulse probability by reaction with a single triggering of a single-photon detector composed of indium-gallium arsenide/indium phosphide single-photon avalanche diodes. Analysis of approaches to estimating the afterpulse used in real-world quantum key distribution systems was performed. The advantages of the developed approach over the standard methods that do not take into account the non-Markov nature of the effect under consideration are demonstrated. Practical significance. The proposed approach was developed in the form of two models (simple and complex), which allows a compromise between the accuracy of calculations and their complexity for the application of such devices in quantum key distribution systems.
Subject of study. A noise parameter, such as an afterpulse effect, that occurs in indium-gallium arsenide/indium phosphide single-photon avalanche diodes when operated as part of a single-photon detector in quantum key distribution systems was investigated. The aim of this study was the analysis of indium-gallium arsenide/indium phosphide single-photon avalanche diode afterpulse effect estimation approaches for real-world quantum key distribution systems and the development of a measurement technique and model for estimating the afterpulse effect in indium-gallium arsenide/indium phosphide single-photon avalanche diodes. Method. For the experimental measurement of the afterpulse probability in indium-gallium arsenide/indium phosphide single-photon avalanche diodes, a special stand was used. All components of this stand are controlled by LabVIEW software. The developed model of afterpulse probability is based on the non-Markovian character of this effect. Main results. A measurement technique and probabilistic model were developed to estimate the afterpulse based on the recursive nature of this effect in indium-gallium arsenide/indium phosphide single-photon avalanche diodes. This makes it possible to estimate the true value of the afterpulse probability by reaction with a single triggering of a single-photon detector composed of indium-gallium arsenide/indium phosphide single-photon avalanche diodes. Analysis of approaches to estimating the afterpulse used in real-world quantum key distribution systems was performed. The advantages of the developed approach over the standard methods that do not take into account the non-Markov nature of the effect under consideration are demonstrated. Practical significance. The proposed approach was developed in the form of two models (simple and complex), which allows a compromise between the accuracy of calculations and their complexity for the application of such devices in quantum key distribution systems.
A sine-gated single-photon detector (SPD) intended for use in a quantum key distribution (QKD) system is considered in this paper. An "avalanche delay" effect in the sine-gated SPD is revealed. This effect consists in the appearance of an avalanche triggered at the next gate after the photon arrival gate. It has been determined experimentally that the nature of this effect is not related to the known effects of afterpulsing or charge persistence. This effect negatively affects the overall error rate in the QKD system. The influence of the main detector control parameters, such as temperature, gate amplitude and comparator's threshold voltage, on the avalanche delay effect was experimentally established.
The application of quantum key distribution (QKD) has raised particular demands for single-photon detectors. One of the most promising candidates at the low-loss optical fibre communications windows is the planar geometry InGaAs/InP single-photon avalanche diode. These detectors have been modelled, fabricated and characterised at 1.55 µm wavelength. Their performance in terms of single-photon detection efficiency, dark count rate, timing jitter and afterpulsing behaviour are reported and compared with the best commercially available, linear multiplication avalanche photodiodes operated in Geiger-mode. Their use in the application of QKD is discussed.
The afterpulse effect is an undesirable phenomenon that occurs in single-photon avalanche diodes (SPADs). SPADs are widely employed in quantum key distribution (QKD) systems. As QKD systems advance to support higher data rates, the minimization of afterpulses becomes increasingly critical. In this paper, we introduce what we believe to be a new structure for the BB84 QKD protocol to reduce afterpulses in QKD systems. The proposed method does not change the secure key rate compared to the conventional BB84 protocol. We conduct a theoretical analysis and simulation of the performance of a single-photon-based QKD system utilizing SPADs with suboptimal afterpulse characteristics. Our results indicate that the afterpulse probability (Pa) in SPADs does not impose a strict lower bound on the error rate of sifted keys in single-photon-based QKD systems. The system utilizes a simplified version of the two-bases BB84 protocol, which operates over fiber-optic or free-space channels. In the proposed structure, eight detectors are used to measure four polarization angles, yielding four possible outcomes. The findings emphasize the practicality of this setup for both fiber-based and free-space quantum communication, making it highly suitable for real-world applications. The afterpulse decay is dependent on an exponential function and changes proportionally to the elapsed time, the number of trapped carriers, the carrier lifetime, the field strength, and the temperature. The project team has extensive experience in afterpulse reduction and has published several papers on the subject. Using the idea presented in this paper, by doubling the receiver detectors under the same conditions, the probability of afterpulse occurrence is approximately halved. We are looking to propose new structures and protocols to reduce undesired pulses in single-photon avalanche detectors.
There is no doubt that measurement-device-independent quantum key distribution (MDI-QKD) is a crucial protocol that is immune to all possible detector side channel attacks. In the preparation phase, a simulation model is usually employed to get a set of optimized parameters, which is utilized for getting a higher secure key rate in reality. With the implementation of high-speed QKD, the afterpulse effect which is an intrinsic characteristic of the single-photon avalanche photodiode is no longer ignorable, this will lead to a great deviation compared with the existing analytical model. Here we develop an afterpulse-compatible MDI-QKD model to get the optimized parameters. Our results indicate that by using our afterpulse-compatible model, we can get a much higher key rate than the prior afterpulse-omitted model. It is significant to take the afterpulse effect into consideration because of the improvement of the system working frequency.
The afterpulse effect is an undesirable phenomenon that occurs in single-photon avalanche diodes (SPADs). SPADs are widely employed in quantum key distribution (QKD) systems. As QKD systems advance to support higher data rates, the minimization of afterpulses becomes increasingly critical. In this paper, we introduce new structure for BB84 QKD protocol to reduce afterpulses in QKD systems. The proposed method does not change secure key rate compared to the conventional BB84 protocol. We conduct a theoretical analysis and simulation of the performance of a single-photon-based QKD system utilizing SPADs with suboptimal afterpulse characteristics. Our results indicate that the afterpulse probability (Pa) in SPADs does not impose a strict lower bound on the error rate of sifted keys in single-photon-based QKD systems. The system utilizes a simplified version of the two-bases BB84 protocol, which operates over fiber-optic or free-space channels. In the proposed structure, eight detectors are used to measure four polarization angles, yielding four possible outcomes. The findings emphasize the practicality of this setup for both fiber-based and free-space quantum communication, making it highly suitable for real-world applications. The afterpulse decay is dependent on an exponential function and changes proportionally to the elapsed time, the number of trapped carriers, the carrier lifetime, the field strength, and the temperature. The project team has extensive experience in afterpulse reduction and has published several papers on the subject. Using the idea presented in this paper, by doubling the receiver detectors under the same conditions, the probability of afterpulse occurrence is approximately halved. We are looking to propose new structures and protocols to reduce undesired pulses in single-photon avalanche detectors.