Yin Hua-Lei, Liu Peng, Dai Wei-Wei, Ci Zhao-Hui, Gu Jie, Gao Tian, Wang Qiang-Wei, Shen Zi-Yao
Opt Express. 2020 Sep 28;28(20):29479-29485. doi: 10.1364/OE.401829.
Quantum key distribution (QKD) promises provably secure communications. In order to improve the secret key rate, combining a biased basis choice with the decoy-state method is proposed. Concomitantly, there is a basis-independent detection efficiency condition, which usually cannot be satisfied in a practical system, such as the time-phase encoding. Fortunately, this flaw has been recently removed theoretically and experimentally in the four-intensity decoy-state BB84 QKD protocol using the fact that the expected yields of single-photon states prepared in two bases stay the same for a given measurement basis. However, the security proofs do not fully consider the finite-key effects for general attacks. In this work, we provide the rigorous finite-key security bounds in the universally composable framework for the four-intensity decoy-state BB84 QKD protocol. We build a time-phase encoding system with 200 MHz clock to implement this protocol, in which the real-time secret key rate is more than 60 kbps over 50 km single-mode fiber.
量子密钥分发（QKD）有望实现可证明的安全通信。为了提高密钥率，人们提出将有偏基选择与诱骗态方法相结合。与此同时，存在一个与基无关的探测效率条件，在诸如时间相位编码等实际系统中通常无法满足。幸运的是，最近在四强度诱骗态BB84 QKD协议中，利用在给定测量基下两个基中制备的单光子态的预期产率保持相同这一事实，从理论和实验上消除了这一缺陷。然而，安全性证明并未充分考虑一般攻击的有限密钥效应。在这项工作中，我们在通用可组合框架下为四强度诱骗态BB84 QKD协议提供了严格的有限密钥安全性界限。我们构建了一个具有200 MHz时钟的时间相位编码系统来实现该协议，其中在50 km单模光纤上实时密钥率超过60 kbps。
