弱极限之外的弱值：后选择下的测量强度不变性
Weak Values Beyond the Weak Limit: Measurement-Strength Invariance Under Post-Selection
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中文总结 AI 辅助
本文发现一类测量协议中，后选择条件值精确独立于探针强度，与弱值实部一致，证明弱耦合并非获取弱值的必要条件。
中文摘要 AI 辅助
弱值通常在测量强度趋近于零的极限下提取。在有限强度下，相应的后选择条件平均值通常会获得非线性修正，且不一定保留其弱值解释。在此，我们识别出一类测量协议，使得这一预期失效：从测量探针重建的条件值精确地独立于探针强度，因此与弱值的实部一致。我们首先在Lund和Wiseman引入的测量-扰动协议中分析这一现象。随后，我们建立了这种不变性持续存在的条件，表明它由探针相互作用、随后与辅助装置的测量相互作用以及最终的后选择之间的相互作用决定。这些结果表明，弱耦合虽然通常足以获取弱值，但并非总是必要的。
英文摘要
Weak values are conventionally extracted in the limit of vanishing measurement strength. At finite strength, the corresponding post-selected conditional averages generally acquire nonlinear corrections and need not retain their weak value interpretation. Here we identify a class of measurement protocols for which this expectation fails: the conditional value reconstructed from the measuring probe is exactly independent of the probe strength and therefore coincides with the real part of the weak value. We first analyze this phenomenon in the measurement--disturbance protocol introduced by Lund and Wiseman. We then establish conditions under which this invariance persists, showing that it is determined by the interplay between the probe interaction, a subsequent measurement interaction with an ancillary apparatus, and the final post-selection. These results demonstrate that weak coupling, although generally sufficient for accessing weak values, is not always necessary.
发表机构
- University of Oxford（牛津大学）
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