基于低损耗多芯光纤的空分复用量子密钥分配  

Space Division Multiplexing Quantum Key Distribution Based on Low Loss Multi-Core Fiber

作　　者：赵良圆 张功会 孙伟 徐东 韦峥 梁洪源 王林[2] Zhao Liangyuan;Zhang Gonghui;Sun Wei;Xu Dong;Wei Zheng;Liang Hongyuan;Wang Lin(Jiangsu Hengtong Qasky Quantum Information Research Institute Co.,Ltd.,Suzhou 215200,Jiangsu,China;Jiangsu Alpha Optic-Electric Technology Co.,Ltd.,Suzhou 215200,Jiangsu,China)

机构地区：[1]江苏亨通问天量子信息研究院有限公司,江苏苏州215200 [2]江苏亨通光纤科技有限公司,江苏苏州215200

出　　处：《光学学报》2024年第16期338-346,共9页Acta Optica Sinica

基　　金：江苏省产业前瞻与关键核心技术竞争项目(BE2021047);江苏省产业前瞻与关键核心技术重点项目(BE2022055)。

摘　　要：基于商用4芯低损耗多芯光纤(MCF)和相位编码量子密钥分配(QKD)系统,实验验证空分复用-量子密钥分配(SDM-QKD)方案的实际产业化可行性。通过超过4 h不间断运行,当共纤传输距离为21.39 km时,QKD的安全密钥率平均值为2.90 kbit/s,量子比特误码率平均值为0.88%;当共纤传输距离为42.78 km时,QKD的安全密钥率平均值为0.75 kbit/s,量子比特误码率平均值为2.15%。与量子信号单独占用一根光纤时QKD的性能进行对比,商用多芯光纤的芯间串扰对QKD信噪比的影响较小,表明基于商用多芯光纤可实现SDM-QKD的实际部署和应用。Objective With the continuous advancement of multi-core fiber(MCF)preparation technology,multiple signals can now be transmitted simultaneously through different cores within a single fiber,enabling space division multiplexing(SDM)co-transmission of quantum and classical signals.This addresses the previous issue of quantum signals monopolizing individual fibers in quantum key distribution(QKD)systems.Despite advancements,previous SDM-QKD experiments using MCF have encountered limitations:limited fiber length,higher attenuation coefficients compared to standard single-core fibers,and lower inter-core crosstalk in laboratory-customized MCFs.We pioneer the practical industrial feasibility of SDM-QKD using commercial 4-core low-loss MCF and phase-coded QKD,demonstrating SDM of quantum and classical signals under realistic urban conditions.This verification provides crucial feasibility for future large-scale deployment of SDM-QKD in urban fiber optic networks.Methods The SDM-QKD experimental setup utilizes a commercial 4-core MCF and phase-coded QKD.Quantum and synchronous QKD signals occupy one core,while classical data signals occupy another core within the 4-core MCF.The MCF has a length of 21.39 km with a cladding diameter of 125μm and core-to-core spacing of 43μm.The cores are sequentially numbered clockwise as 1#,2#,3#,and 4#.Each core exhibits an attenuation coefficient of 0.182 dB/km@1550 nm with inter-core crosstalk coefficients ranging from 10^(−7)km^(−1).Spatial coupling and decoupling of signals across cores are achieved using 1×^(4)fan-in/fan-out devices with an insertion loss of 0.9 dB and an isolation degree of 50 dB.The experiment employs a commercial QKD device based on the phase-encoding decoy-state BB84 protocol with a Faraday-Michelson interferometer.The emission frequency of quantum signals is 50 MHz,with a distribution ratio of 14∶1∶1 among signal,decoy,and vacuum states.The average photon numbers for these states are 0.6,0.2,and 0,respectively.Quantum and synchronous signals at wavele

关 键 词：量子光学 量子密钥分配 量子密码 多芯光纤 空分复用 同纤共传 

分 类 号：O431.2[机械工程—光学工程]