基于广义算符优势条件的双场量子密钥分发的密钥分析
Finite-key analysis for twin-field quantum key distribution based on generalized operator dominance condition
摘要：
量子密钥分发（QKD）可以帮助两个相距遥远的节点共享密钥比特，其安全性由物理定律保证。在实际应用中，随着信道距离的增加，QKD协议的密钥速率会降低，这严重限制了QKD的应用。近年来，双场量子密钥分配（TF QKD）由于能够突破量子密钥分配的速率-距离限制，极大地提高量子密钥分配的可达距离而被提出并得到广泛研究。很明显，K。Maeda et.等人提出了一种基于算子优势条件的TF-QKD有限密钥分析方法。虽然他们证明了他们的方法足以克服速率-距离限制，但他们的算子优势条件并不普遍，即它只能适用于三个诱饵态的情况，这意味着它的密钥速率不能通过引入更多的诱饵态来提高，即使在准备无限个诱饵态和光脉冲的情况下也不能达到渐近界。在这里，为了弥补这一差距，我们提出了一种改进的有限密钥分析的TF-QKD通过设计新的运营商的优势条件。我们证明了通过增加诱饵状态的数目，密钥速率可以进一步提高，并接近渐近界。我们的理论可以直接应用于TF-QKD实验中，以获得更高的密钥速率。我们的结果可以直接用于实验，以获得更高的密钥速率。
英文摘要：
Quantum key distribution (QKD) can help two distant peers to share secret key bits, whose security is guaranteed by the law of physics. In practice, the secret key rate of a QKD protocol is always lowered with the increasing of channel distance, which severely limits the applications of QKD. Recently, twin-field (TF) QKD has been proposed and intensively studied, since it can beat the rate-distance limit and greatly increase the achievable distance of QKD. Remarkalebly, K. Maeda et. al. proposed a simple finite-key analysis for TF-QKD based on operator dominance condition. Although they showed that their method is sufficient to beat the rate-distance limit, their operator dominance condition is not general, i.e. it can be only applied in three decoy states scenarios, which implies that its key rate cannot be increased by introducing more decoy states, and also cannot reach the asymptotic bound even in case of preparing infinite decoy states and optical pulses. Here, to bridge this gap, we propose an improved finite-key analysis of TF-QKD through devising new operator dominance condition. We show that by adding the number of decoy states, the secret key rate can be furtherly improved and approach the asymptotic bound. Our theory can be directly used in TF-QKD experiment to obtain higher secret key rate. Our results can be directly used in experiments to obtain higher key rates.
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