• Photonics Research
  • Vol. 12, Issue 6, 1262 (2024)
Dengke Qi1,2, Xiangyu Wang1,*, Zhenghua Li1, Jiayu Ma1..., Ziyang Chen3, Yueming Lu2 and Song Yu1|Show fewer author(s)
Author Affiliations
  • 1State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China
  • 2Key Laboratory of Trustworthy Distributed Computing and Service (MoE), Beijing University of Posts and Telecommunications, Beijing 100876, China
  • 3State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Electronics, and Center for Quantum Information Technology, Peking University, Beijing 100871, China
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    DOI: 10.1364/PRJ.519140 Cite this Article Set citation alerts
    Dengke Qi, Xiangyu Wang, Zhenghua Li, Jiayu Ma, Ziyang Chen, Yueming Lu, Song Yu, "Experimental demonstration of a quantum downstream access network in continuous variable quantum key distribution with a local local oscillator," Photonics Res. 12, 1262 (2024) Copy Citation Text show less

    Abstract

    Quantum networks provide opportunities and challenges across a range of intellectual and technical frontiers, including quantum computation, communication, and others. Unlike traditional communication networks, quantum networks utilize quantum bits rather than classical bits to store and transmit information. Quantum key distribution (QKD) relying on the principles of quantum mechanics is a key component in quantum networks and enables two parties to produce a shared random secret key, thereby ensuring the security of data transmission. In this work, we propose a cost-effective quantum downstream access network structure in which each user can get their corresponding key information through terminal distribution. Based on this structure, we demonstrate the first four-end-users quantum downstream access network in continuous variable QKD with a local local oscillator. In contrast to point-to-point continuous variable QKD, the network architecture reevaluates the security of each user and accounts for it accordingly, and each user has a lower tolerance for excess noise as the overall network expands with more users. Hence, the feasibility of the experiment is based on the analysis of the theoretical model, noise analysis, and multiple techniques such as the particle filter and adaptive equalization algorithm used to suppress excess noise. The results show that each user can get a low level of excess noise and can achieve secret key rates of 546 kbps, 535 kbps, 522.5 kbps, and 512.5 kbps under a transmission distance of 10 km, respectively, with the finite-size block of 1×108. This not only verifies the good performance but also provides the foundation for the future multi-user quantum downstream access networks.
    K=βIAC1χEC1,

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    K=KχC1C2χC1C3χC1C4,

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    K=βIAC1χEC1,

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    εtotal=εtrust+εuntrust=εDet+εADC+εRIN+εDAC+εMod+εPhase,

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    εDet=2NEP2BτfPLO,

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    εADC=2τfg2ρ2PLO112RU222n,

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    εRIN=VARINsigΔvQLT+14TRINLOΔvQNUVRIN(q^),

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    εDAC=VA[πδVDACVDAC+π22(δVDACVDAC)2]2,

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    εMod=|as|210ddB/10,

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    ddB=10log10(Emax2Emin2),

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    εPhase=εfast+εslow,

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    X(k)=H(k)X(k1)+W(k1),

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    Z(k)=g(X(k))+V(k).

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    y(n)=w(n)x(n).

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    εremain=εerrorεRLS-com,

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    Esig=Asigcos(2πfAt+φQLT+φsig),

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    Eref=Arefcos(2πfAt+φQLT),

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    ELO=ALOcos(2πfBt+φQNU1),

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    Isig=Rη(|Esig+ELO|2|EsigELO|2)=2RηAsigALOcos(2πΔfABt+φsig+Δφfast+Δφslow),

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    Iref=Rη(|Eref+ELO|2|ErefELO|2)=2RηArefALOcos(2πΔfABt+Δφfast),

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    Xsig=LPF(real(Isig·e2πΔfABt))=RηAsigALOcos(φsig+Δφfast+Δφslow),

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    Psig=LPF(imag(Isig·e2πΔfABt))=RηAsigALOsin(φsig+Δφfast+Δφslow),

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    Xref=LPF(real(Iref·e2πΔfABt))=RηArefALOcos(Δφfast),

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    Pref=LPF(imag(Iref·e2πΔfABt))=RηArefALOsin(Δφfast),

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    Xsig=XsigcosθfastPsigsinθfast=RηAsigALOcos(φsig+Δφslow),

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    Psig=XsigsinθfastPsigcosθfast=RηAsigALOsin(φsig+Δφslow).

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    XB=XsigcosθslowPsigsinθslow=RηAsigALOcos(φsig),

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    PB=XsigsinθslowPsigcosθslow=RηAsigALOsin(φsig).

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    X(k)=H(k)X(k1)+W(k1),(A1)

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    Z(k)=g(X(k))+V(k),(A2)

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    w(k)i=1N=Ki(k)w(k1)i=1N,(A3)

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    ε(n)=d(n)wT(n1)x(n),(B1)

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    k(n)=P(n1)x(n)λ+xT(n)P(n1)x(n),(B2)

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    P(n)=1λ[P(n1)k(n)xT(n)P(n1)],(B3)

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    ω(n)=ω(n1)+k(n)ε(n),(B4)

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    y(n)=ω(n)x(n).(B5)

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    K=fsym·nN[βIABχBEΔ(n)],(C1)

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    IAB=log2(V+χtot1+χtot),(C2)

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    χBE=i=12G(λi12)i=35G(λi12),(C3)

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    λ1,22=12(A±A24B),λ3,42=12(C±C24D),λ5=1,(C4)

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    A=V2(12T)+2T+T2(V+χline)2,B=T2(Vχline+1)2,C=1T2(V+χtot)2{Aχhet2+B+1+2χhet[VB+T(V+χline)]+2T(V21)},D=[V+BχhetT(V+χtot)]2.(C5)

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    Tmin=(ηTΔT)2η,εmax=ε+Δσ02ηT,(C6)

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    ΔT=ζδPE/2σ2mVA,Δσ02=ζδPE/2σ22m,(C7)

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    Δ(n)=7log2(1/ζ)n+2nlog21ζPA,(C8)

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    Dengke Qi, Xiangyu Wang, Zhenghua Li, Jiayu Ma, Ziyang Chen, Yueming Lu, Song Yu, "Experimental demonstration of a quantum downstream access network in continuous variable quantum key distribution with a local local oscillator," Photonics Res. 12, 1262 (2024)
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