论文标题
相干量子密钥分布的上限范围
Upper security bounds for coherent-one-way quantum key distribution
论文作者
论文摘要
量子键分布（QKD）的性能受到由于光子数分裂攻击而引起的激光源发出的多光子脉冲。引入了连贯的一路（牛）QKD，作为克服这一限制的有前途的解决方案，从而扩大了实际QKD的可实现距离。确实，由于其实验性的简单性，牛协议已经用于商业应用中。在这里，我们在其秘密关键速度上得出了简单的上限范围，这表明它最多可以与系统的传输相规，从而解决了一个长期存在的问题。也就是说，与所声称的相反，这种方法不适合长途QKD传输。值得注意的是，我们的发现表明，到目前为止执行的牛协议的所有实施都是不安全的。
The performance of quantum key distribution (QKD) is severely limited by multi-photon pulses emitted by laser sources due to the photon-number splitting attack. Coherent-one-way (COW) QKD has been introduced as a promising solution to overcome this limitation, and thus extend the achievable distance of practical QKD. Indeed, thanks to its experimental simplicity, the COW protocol is already used in commercial applications. Here, we derive simple upper security bounds on its secret key rate, which demonstrate that it scales at most quadratically with the system's transmittance, thus solving a long-standing problem. That is, in contrast to what has been claimed, this approach is inappropriate for long-distance QKD transmission. Remarkably, our findings imply that all implementations of the COW protocol performed so far are insecure.
