Beating the Fundamental Rate-Distance Limit in a Proof-of-Principle Quantum Key Distribution System
Beating the Fundamental Rate-Distance Limit in a Proof-of-Principle Quantum Key Distribution System
复制标题
突破原理验证量子密钥分配系统中的基本速率距离限制
DOI：
10.1103/physrevx.9.021046
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发表时间：
2019-06-04
影响因子：
12.5
通讯作者：
Han, Zheng-Fu
中科院分区：
文献类型：
--
作者：
Wang, Shuang;He, De-Yong;Han, Zheng-Fu
在量子密钥分发（QKD）的帮助下，两个遥远的对等体能够共享信息理论安全的密钥比特。提高密钥速率对于QKD在有损信道中的应用具有重要意义。然而，它已被证明，有一个基本的速率距离限制，称为线性界限，这限制了所有现有的无中继协议和实现的性能。令人惊讶的是，最近提出的一种称为双场（TF）QKD的协议可以在不需要量子中继器的情况下击败线性约束。在这里，我们提出了TF-QKD协议的第一个实现之一，并展示了其在300公里的信道距离上击败线性约束的优势。在我们的实验中，一个修改后的TF-QKD协议，不假设相位后选择被认为是，因此，一个更高的密钥速率比原来的。在控制通过数百公里光纤传播的双场的相位演化后，所实现的系统实现了高可见性的单光子干涉，并允许稳定且高速的独立于测量设备的QKD。实验证明了TF-QKD协议的可行性及其在远距离密钥分发服务中的突出优势。
With the help of quantum key distribution (QKD), two distant peers are able to share information-theoretical secure key bits. Increasing the key rate is ultimately significant for the applications of QKD in the lossy channel. However, it has been proven that there is a fundamental rate-distance limit, called the linear bound, which restricts the performance of all existing repeaterless protocols and realizations. Surprisingly, a recently proposed protocol, called twin-field (TF) QKD, can beat the linear bound with no need for quantum repeaters. Here, we present one of the first implementations of the TF-QKD protocol and demonstrate its advantage of beating the linear bound at a channel distance of 300 km. In our experiment, a modified TF-QKD protocol that does not assume phase postselection is considered, and thus a higher key rate than the original one is expected. After controlling the phase evolution of the twin fields traveling through hundreds of kilometers of optical fibers, the implemented system achieves high-visibility single-photon interference and allows stable and high-rate measurement-device-independent QKD. Our experimental demonstration and results confirm the feasibility of the TF-QKD protocol and its prominent superiority in long-distance key distribution services.