Lim Charles Ci-Wen, Xu Feihu, Pan Jian-Wei, Ekert Artur
Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583.
Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543.
Phys Rev Lett. 2021 Mar 12;126(10):100501. doi: 10.1103/PhysRevLett.126.100501.
The security of real-world quantum key distribution (QKD) critically depends on the number of data points the system can collect in a finite time interval. To date, state-of-the-art finite-key security analyses require block lengths in the order of 10^{4} bits to obtain positive secret keys. This requirement, however, can be very difficult to achieve in practice, especially in the case of entanglement-based satellite QKD, where the overall channel loss can go up to 70 dB or more. Here, we provide an improved finite-key security analysis which reduces the block length requirement by 14% to 17% for standard channel and protocol settings. In practical terms, this reduction could save entanglement-based satellite QKD weeks of measurement time and resources, thereby bringing space-based QKD technology closer to reality. As an application, we use the improved analysis to show that the recently reported Micius QKD satellite is capable of generating positive secret keys with a 10^{-5} security level.
现实世界中量子密钥分发（QKD）的安全性严重依赖于系统在有限时间间隔内能够收集的数据点数。迄今为止，最先进的有限密钥安全性分析要求块长度达到10⁴比特量级才能获得正的秘密密钥。然而，这一要求在实践中可能很难实现，特别是在基于纠缠的卫星QKD的情况下，其中整体信道损耗可能高达70分贝或更高。在此，我们提供了一种改进的有限密钥安全性分析，对于标准信道和协议设置，它将块长度要求降低了14%至17%。实际上，这种降低可以为基于纠缠的卫星QKD节省数周的测量时间和资源，从而使天基QKD技术更接近现实。作为一个应用，我们使用改进后的分析表明，最近报道的墨子号QKD卫星能够生成具有10⁻⁵安全级别的正秘密密钥。
