鲁棒量子密钥分发：任意接近局域关联的情况
Robust Quantum Key Distribution Arbitrarily Close to Local Correlations
浏览论文内容
中文总结 AI 辅助
该研究针对设备无关量子密钥分发，证明贝尔违背接近Tsirelson界时可产生恒定密钥率，还通过半定松弛数值结果显示实用手段可保证非零密钥率。
中文摘要 AI 辅助
近期，Wooltorton等人[Phys. Rev. Lett. 132, 210802 (2024)]与Farkas[Phys. Rev. Lett. 132, 210803 (2024)]揭示了设备无关量子密钥分发中，贝尔不等式违背与其密码应用之间存在不匹配：在任意接近局域行为集合的范围内，存在量子关联可保证恒定的秘密密钥率。这些结果要求关联达到合适贝尔可观测量的最大量子值（即Tsirelson界），并依赖于对最大纠缠态及相关贝尔测量的理想自测试。本文证明该效应具有鲁棒性：对于Wooltorton等人考虑的每一个贝尔不等式，只要观测到的贝尔违背足够接近各自的Tsirelson界，就会产生恒定的秘密密钥率。针对这些贝尔不等式以及Farkas的贝尔不等式，本文还基于与特定贝尔违背一致的最小最小熵的半定松弛给出了数值结果，表明通过实用且高效的手段，原则上可保证存在小但非零的密钥率。
英文摘要
Recently, Wooltorton et al. [Phys. Rev. Lett. 132, 210802 (2024)] and Farkas [Phys. Rev. Lett. 132, 210803 (2024)] have exhibited the mismatch between Bell inequality violations and their cryptographic application in device-independent quantum key distribution, by showing that arbitrarily close to the set of local behaviours there exist quantum correlations guaranteeing a constant rate of secret key. While these results require correlations attaining the maximum quantum value of a suitable Bell observable (aka the Tsirelson bound) and rely on a kind of ideal self-testing of a maximally entangled state and associated Bell measurement, here we show that the effect is robust: for every one of the Bell inequalities considered by Wooltorton \emph{et al.}, a constant rate of secret key ensues if the observed Bell violation is sufficiently close to the respective Tsirelson bound. For these and also the Bell inequalities of Farkas, we furthermore present numerical results based on semidefinite relaxations of the minimum min-entropy consistent with a certain Bell violation, which demonstrate that small but nonzero key rates can be guaranteed (in principle) by practical and efficient means.
