Li Bing-Hong, Xie Yuan-Mei, Li Zhao, Weng Chen-Xun, Li Chen-Long, Yin Hua-Lei, Chen Zeng-Bing
Opt Lett. 2021 Nov 15;46(22):5529-5532. doi: 10.1364/OL.443099.
Twin-field quantum key distribution (TFQKD), using single-photon-type interference, offers a way to exceed the rate-distance limit without quantum repeaters. However, it still suffers from photon losses and dark counts, which impose an ultimate limit on its transmission distance. In this Letter, we propose a scheme to implement TFQKD with an entangled coherent state source in the middle to increase its range, as well as comparing its performance under coherent attacks with that of TFQKD variants. Simulations show that our protocol has a theoretical distance advantage of 400 km. Moreover, the scheme has great robustness against the misalignment error and finite-size effects. Our work is a promising step toward long-distance secure communication and is greatly compatible with future global quantum networks.
双场量子密钥分发（TFQKD）利用单光子型干涉，提供了一种无需量子中继器即可突破速率 - 距离限制的方法。然而，它仍然受到光子损失和暗计数的影响，这对其传输距离施加了最终限制。在本信函中，我们提出了一种方案，在中间使用纠缠相干态源来实现TFQKD，以增加其范围，并将其在相干攻击下的性能与TFQKD变体的性能进行比较。模拟表明，我们的协议具有400公里的理论距离优势。此外，该方案对失准误差和有限尺寸效应具有很强的鲁棒性。我们的工作是朝着长距离安全通信迈出的有希望的一步，并且与未来的全球量子网络具有很大的兼容性。
