Abstract
Long-distance quantum key distribution (QKD) has long time seriously relied on trusted relay or quantum repeater, which either has security threat or is far from practical implementation. Recently, a solution called twin-field (TF) QKD and its variants have been proposed to overcome this challenge. However, most security proofs are complicated, a majority of which could only ensure security against collective attacks. Until now, the full and simple security proof can only be provided with asymptotic resource assumption. Here, we provide a composable finite-key analysis for coherent-state-based TF-QKD with rigorous security proof against general attacks. Furthermore, we develop the optimal statistical fluctuation analysis method to significantly improve secret key rate in high-loss regime. The results show that coherent-state-based TF-QKD is practical and feasible, with the potential to apply over nearly one thousand kilometers.
Highlights
Long-distance quantum key distribution (QKD) has long time seriously relied on trusted relay or quantum repeater, which either has security threat or is far from practical implementation
We provide a composable finite-key analysis for coherent-state-based TF-QKD with rigorous security proof against general attacks
Our simulation result shows clearly that coherent-state-based TF-QKD is the feasible scheme in the finite-key regime
Summary
Long-distance quantum key distribution (QKD) has long time seriously relied on trusted relay or quantum repeater, which either has security threat or is far from practical implementation. To overcome the side-channel attacks on detection, the measurement-device-independent (MDI) QKD based on two-photon Bell state measurement[11] has been proposed and experimentally demonstrated over 404 km ultralow-loss fibre[12]. A novel protocol known as twin-field (TF) QKD14 has been introduced to simultaneously solve the above two problems by exploiting the single-photon interference in the untrusted relay, which provides a secret key rate proportional to the square-root of channel transmittance and is immune to any attack on measurement devices. One is the single-photon-based TF-QKD21,22,24 first proposed in ref.[21] named as sending-or-not-sending protocol with a security proof against coherent attack It is similar with the original TF-QKD using the single-photon component to extract secret key by implementing single-photon Bell state measurement[22,24]. Taking into account all finite-size effects in TF-QKD with rigorously composable security proof is still missing, which severely influences TF-QKD to become as practical and feasible as typical QKD29,30 and MDI-QKD31 with composable security under realistic conditions
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