Zeng Pei, Zhou Hongyi, Wu Weijie, Ma Xiongfeng
Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, 100084, China.
Nat Commun. 2022 Jul 7;13(1):3903. doi: 10.1038/s41467-022-31534-7.
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 [Formula: see text] 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 [Formula: see text] 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.
量子密钥分发——基于量子物理建立信息理论上安全的密钥——主要受其实际性能的限制，其特点是密钥率依赖于信道透射率R(η)。最近，有人提出基于单光子干涉的方案，通过克服干涉仪的点对点密钥容量限制，将密钥率提高到[公式：见正文]。不幸的是，所有这些方案都需要具有挑战性的全局锁相，以实现一个稳定的长臂单光子干涉仪，其精度在数百公里长的光纤上约为100纳米。为了解决这个问题，我们提出了一种模式配对测量设备无关量子密钥分发方案，其中编码的密钥比特和基在数据后处理期间确定。使用传统的二阶干涉，当局部相位波动较小时，该方案无需全局锁相即可实现[公式：见正文]的密钥率。我们期望这种高性能方案能够用现成的光学器件实现。
