论文标题
量子密钥分布超过无关的速率传递，而无需全局锁定
Quantum key distribution surpassing the repeaterless rate-transmittance bound without global phase locking
论文作者
论文摘要
量子密钥分布（基于量子物理学的理论上安全键的建立）主要受其实际性能的限制，其特征在于关键率对渠道传输$ r（η）$的依赖性。最近，已经提出了基于单光子干扰的方案，以克服与干涉仪结合的点对点秘密关键容量，将关键率提高到$ r = o（\sqrtη）$。不幸的是，所有这些方案都需要具有挑战性的全球相位锁定，以实现稳定的长臂单光子干涉仪，其精度比数百公里长的纤维精度约为100 nm。为了解决这个问题，我们提出了一个模式对测量设备与量子密钥分布方案，其中在数据后处理过程中确定了编码的密钥位和碱基。使用常规的二阶干扰，该方案可以达到$ r = O（\sqrtη）$的关键率，而当局部相位波动轻度时，无全球相位锁定。我们希望这种高性能方案将使用现成的光学设备即将实现。
Quantum key distribution -- the establishment of information-theoretically secure keys based on quantum physics -- is mainly limited by its practical performance, which is characterised by the dependence of the key rate on the channel transmittance $R(η)$. Recently, schemes based on single-photon interference have been proposed to improve the key rate to $R=O(\sqrtη)$ by overcoming the point-to-point secret key capacity bound with interferometers. Unfortunately, all of these schemes require challenging global phase locking to realise a stable long-arm single-photon interferometer with a precision of approximately 100 nm over fibres that are hundreds of kilometres long. Aiming to address this problem, we propose a mode-pairing measurement-device-independent quantum key distribution scheme in which the encoded key bits and bases are determined during data post-processing. Using conventional second-order interference, this scheme can achieve a key rate of $R=O(\sqrtη)$ without global phase locking when the local phase fluctuation is mild. We expect this high-performance scheme to be ready-to-implement with off-the-shelf optical devices.
