InGaAs/InP高速正弦门控单光子探测器后脉冲抑制方案

Afterpulse suppression scheme of InGaAs/InP high speed sinusoidal gated single photon detector

基于量子力学基本原理的量子密钥分发(QKD)系统具有信息论安全的水平,单光子探测器是QKD系统的重要组成,其后脉冲对QKD系统的安全成码率和安全成码距离均有重要影响。文中根据InGaAs/InP高速正弦门控探测器的后脉冲概率随时间呈现指数递减分布的规律,提出了一种基于时间测量的后脉冲抑制方案,采用“Start-Stop型”时间间隔测量方式对探测脉冲进行测量,通过对探测事件进行时间标记并舍弃一段时长内探测脉冲的方法降低了后脉冲概率。实际验证了某型号单光子探测器的后脉冲概率随舍弃时长的关系,在500 ns舍弃时长条件下,后脉冲概率2.46%,增加舍弃时长至5μs可降低后脉冲至2%以下。同时,分析了100 ns舍弃时长条件下的典型探测脉冲计数分布,指出了主要后脉冲分布区域以及未过甄别阈值的雪崩脉冲引起的后脉冲机理。进一步地,指出基于时间测量方式区分探测脉冲的到达时间不仅可用于降低单光子探测的后脉冲概率,还可以根据探测脉冲的到达时间识别雪崩过渡区攻击事件、门外攻击事件,从而丢弃被攻击区域的探测脉冲来提升QKD系统抗量子黑客攻击的能力,可支撑高速正弦门控单光子探测器应用于实用化的QKD系统。

Objective Quantum key distribution(QKD)system based on the basic principles of quantum mechanics can reach the level of information theory security.Single photon detector is an important component of QKD system,and the afterpulse probability has an important effect on the performance of QKD system.In this paper,an InGaAs/InP high sinusoidal gated detector afterpulse suppression scheme is designed to meet the requirements of QKD system.Methods In this paper,according to the law that the probability of the afterpulse of the InGaAs/InP high-speed sinusoidal gated detector shows an exponential decreasing distribution with time,the detection pulse is measured by using the"Start-Stop"time interval measurement method.Each detection pulse is time-marked separately,and the probability of the afterpulse of the detector is reduced by discarding the detection pulse within a certain period of time(Fig.2).Results and Discussions This paper actually verifies the relationship between the afterpulse probability and the discard time of a single photon detector(Fig.5).The main afterpulse distribution area is pointed out and the reason for the depression in the range of discard time is explained(Fig.6).The afterpulse probability under different discard time conditions was calculated.The afterpulse probability is 2.46%when the discard time is 500 ns,and 1.97%when the discard time is 5μs.Furthermore,it is pointed out that distinguishing the arrival time of detection pulse by time measurement can also improve the ability of QKD system to resist quantum hacker attacks such as avalanche transition region attack and behind door attack.Conclusions According to the law that the afterpulse probability of the InGaAs/InP high-speed sinusoidal gated detector is exponentially decreasing with time,a afterpulse suppression scheme based on time measurement is proposed in this paper.The afterpulse probability of the detector is reduced by marking the detection event with time and discarding the detection pulse in a period of time.The proposed afterpulse probability suppression scheme has the characteristics of clear principle and easy engineering implementation,and has no direct influence on the working process of single photon detector,but the detector saturation count rate will decrease with the increase of discard time.At the same time,distinguishing the arrival time of detection pulse by time measurement can also improve the ability of QKD system to resist quantum hacker attacks,and can support the application of high-speed sinusoidal gated single photon detector in QKD system.