Line-of-sight quantum key distribution with differential phase shift keying
Line-of-sight quantum key distribution with differential phase shift keying
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DOI：
10.1088/1367-2630/ac5056
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发表时间：
2022-02-01
影响因子：
3.3
通讯作者：
Sasaki, Masahide
中科院分区：
文献类型：
--
作者：
Endo, Hiroyuki;Sasaki, Toshihiko;Sasaki, Masahide
自由空间光链路（FSO）为在全球范围内实现量子密钥分发（QKD）提供了一种可行的途径。然而，当人们想要进一步扩展从地球静止轨道到地面的距离时，主要由于激光束的衍射损耗，目前已知的QKD方案不能实现实际的密钥速率。如果考虑到FSO链路是高度定向的并且必须在视线（LoS）条件下使用的事实，则可以对窃听模型施加一些物理限制以探索更长距离的QKD。在本文中，我们提出了一种新的FSO密钥协商方案，视线QKD（LoS-QKD），基于量子窃听信道。在我们的模型中，窃听者只能窃听FSO信号波束的有限部分，但对窃听信号执行任何物理上允许的操作。FSO链路中重要的衰落效应被充分考虑。我们提供了一个安全性证明的差分相移（DPS）键控方案的度量，满足可组合性。数值研究了DPS密钥的LoS-QKD方案的性能，包括有限长度分析，结果表明该方案能够实现高速、远距离的密钥协商，且具有信息论安全性。
Free-space optical (FSO) links offer a practical approach to realize quantum key distribution (QKD) in a global scale. However, when one wants to further extend the distance from the geostationary orbit to the ground, currently known QKD schemes cannot realize practical key rates mainly due to the diffraction losses of a laser beam. If the facts that the FSO links are highly directional and must be used in the line-of-sight (LoS) condition are taken into account, one may impose some physical restrictions on an eavesdropping model to explore longer-distance QKD. In this paper, we propose a novel FSO secret key agreement scheme, line-of-sight QKD (LoS-QKD), based on a quantum wiretap channel. In our model, an eavesdropper can tap only a limited fraction of the FSO signal beam but perform any physically allowable operations on the tapped signals. Fading effects which are significant in the FSO links are fully taken into account. We provide a security proof for the differential phase shift (DPS) keying scheme in terms of the metric which meets the composability. We investigate numerically the performances of LoS-QKD with DPS keying, including finite-length analysis, showing that our proposed scheme can realize high-speed and long-distance secret key agreement with information-theoretic security.