Variable-strength nonlocal measurements reveal quantum violations of classical counting principles

• 成果类型: Article
• 署名作者: Lupu-Gladstein, Noah; Pang, Ou Teen Arthur; Ferretti, Hugo; Tham, Weng-Kian; Steinberg, Aephraim M.; Bonsma-Fisher, Kent; Brodutch, Aharon
• 署名单位: University of Toronto; University of Toronto; Canadian Institute for Advanced Research (CIFAR); National Research Council Canada
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-9235
• DOI: 10.1073/pnas.2416331122
• 发表日期: 2025-02-18

摘要

We implement a variant of the quantum pigeonhole paradox thought experiment to study whether classical counting principles survive in the quantum domain. We observe strong measurements significantly violate the pigeonhole principle (that among three pigeons in two holes, at least one pair must be in the same hole) and the sum rule (that the number of pigeon pairs in the same hole is the sum of the number of pairs across each of the holes) in an ensemble that is pre- and postselected into particular separable states. To investigate whether measurement disturbance is a viable explanation for these counterintuitive phenomena, we employ a we employ variable-strength nonlocal measurements. As we decrease the measurement strength, we find the violation of the sum rule decreases, yet the pigeonhole principle remains violated. In the weak limit, the sum rule is restored due to the cancellation between two weak values with equal and opposite imaginary parts. We observe the same kind of cancellation at higher measurement strengths, thus raising the question: do strong measurements have imaginary parts?