检测虚假相关性：发现一个虚假的贝尔不等式违背
Detecting false correlations: Uncovering a faked Bell-inequality violation
摘要：
对于两方，Alice和Bob，可以通过共享纠缠粒子的集合来建立安全的通信链路，然后使用这些粒子来生成密钥。确定粒子确实纠缠的一种方法是验证它们是否违反了贝尔不等式。然而，也可能是Bob不值得信任，希望Alice相信他们的通信是安全的，而事实上他们并不安全。他可以通过设法具有Alice的测量设备设置的先验知识并且然后基于该信息修改他自己的设置来做到这一点。在这种情况下，必须满足贝尔不等式的共享粒子态可能会违反这个不等式，这也会使系统看起来安全。然而，当鲍勃修改他的测量设置时，他会产生错误的相关性。在这里，我们通过实验证明，爱丽丝可以检测到这些错误的相关性，并发现鲍勃的诡计，通过使用循环状态验证和测量（SPAM）断层扫描。更一般地说，我们证明了循环SPAM断层扫描可以检测两个量子比特系统中的错误相关性（相关误差），而不需要知道任何关于准备状态或测量的信息，除了描述它们的算子的维度。
英文摘要：
It is possible for two parties, Alice and Bob, to establish a secure communication link by sharing an ensemble of entangled particles, and then using these particles to generate a secret key. One way to establish that the particles are indeed entangled is to verify that they violate a Bell inequality. However, it might be the case that Bob is not trustworthy and wishes Alice to believe that their communications are secure, when in fact they are not. He can do this by managing to have prior knowledge of Alice's measurement device settings and then modifying his own settings based upon this information. In this case it is possible for shared particle states that must satisfy a Bell inequality to appear to violate this inequality, which would also make the system appear secure. When Bob modifies his measurement settings, however, he produces false correlations. Here we demonstrate experimentally that Alice can detect these false correlations, and uncover Bob's trickery, by using loop-state-preparation-and-measurement (SPAM) tomography. More generally, we demonstrate that loop SPAM tomography can detect false correlations (correlated errors) in a two-qubit system without needing to know anything about the prepared states or the measurements, other than the dimensions of the operators that describe them.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
