Unsharp quantum measurements provide a resource in scenarios where one faces the trade-off between information gain and disturbance. In this work we introduce a prepare-transform-measure scenario in which two-outcome unsharp measurements outperform their sharp counterparts, as well as any stochastic strategy involving dichotomic projective measurements. Based on that, we propose a scheme for semi-device-independent self-testing of unsharp measurements and show that all two-outcome qubit measurements can be characterized in a robust way. Along with the main result, in this work we introduce a method, based on semidefinite programming, for bounding quantum correlations in scenarios with sequential measurements of length 2. This method can also be applied to refine security analysis of the semi-device-independent one-way quantum key distribution. We also present an information gain–disturbance relation for pairs of dichotomic measurements.

中文翻译：

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锐度测量的独立于半设备的自我测试

锐利的量子测量在面临信息增益和干扰之间权衡的情况下提供了一种资源。在这项工作中，我们介绍了一种准备转换测量方案，其中两次结果不清晰的测量结果要优于其尖锐的测量结果，以及任何涉及二分投影测量的随机策略。在此基础上，我们提出了一种针对半独立设备的不清晰测量的自测试方案，并表明可以以可靠的方式表征所有两个结果的量子位测量。连同主要结果，在这项工作中，我们介绍了一种基于半定性编程的方法，用于在长度为2的连续测量的情况下，限制量子相关性。该方法还可以用于改进半独立于设备的安全性分析。双向量子密钥分配。