相干和非相干测量缺陷对多体量子非局域性和量子密钥分发的影响
Effects of coherent and incoherent measurement imperfections on multipartite quantum nonlocality and quantum key distribution
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中文总结 AI 辅助
研究相干和非相干测量缺陷对多体量子非局域性及量子密钥分发的影响，基于MABK等不等式分析其对贝尔值等的作用，还通过与密钥率界限联系得出认证约束，为相关认证和估计提供定量基准。
中文摘要 AI 辅助
多体贝尔非局域性是与设备无关的量子信息协议的核心资源，但其实际认证不可避免地受到不完美测量的影响。我们基于Mermin、Svetlichny和Mermin - Ardehali - Belinskii - Klyshko（MABK）不等式，分析了相干角错位和非相干结果翻转如何影响n体GHZ态中的贝尔值退化和非局域性阈值。相干错位产生周期性的角违反窗口，其单个宽度随粒子数减少。相比之下，非相干结果翻转产生单个临界结果翻转概率，对于MABK和奇数n的Mermin不等式，该概率随n增加，而对于Svetlichny不等式则随n减小。在凸组合攻击模型下，将退化的贝尔值与渐近Devetak - Winter密钥率界限联系起来表明，秘密密钥生成对测量缺陷施加了比非局域性认证更严格的约束。这些结果为测量缺陷下的稳健多体非局域性认证和密钥率估计提供了定量基准。
英文摘要
Multipartite Bell nonlocality is a central resource for device-independent quantum information protocols, but its practical certification is inevitably affected by imperfect measurements. We analyze how coherent angular misalignment and incoherent outcome flipping affect Bell-value degradation and nonlocality thresholds in $n$-partite GHZ states based on the Mermin, Svetlichny, and Mermin--Ardehali--Belinskii--Klyshko (MABK) inequalities. Coherent misalignment produces periodic angular violation windows whose individual widths shrink with the number of parties. In contrast, incoherent outcome flipping yields a single critical outcome-flipping probability, which increases with $n$ for MABK and the odd-$n$ Mermin inequalities, but decreases with $n$ for the Svetlichny inequality. Connecting the degraded Bell values to asymptotic Devetak--Winter key-rate bounds under a convex-combination attack model shows that secret-key generation imposes stricter constraints on measurement imperfections than nonlocality certification. These results provide quantitative benchmarks for robust multipartite nonlocality certification and key-rate estimation under measurement imperfections.
