Unmasking the polygamous nature of quantum nonlocality

• 成果类型: Article
• 署名作者: Cieslinskia, Pawel; Knips, Lukas; Kowalczyk, Mateusz; Laskowski, Wieshw; Paterek, Tomasz; Vertesi, Tamas; Weinfurter, Harald
• 署名单位: Fahrenheit Universities; University of Gdansk; Max Planck Society; University of Munich; Xiamen University Malaysia Campus; HUN-REN; HUN-REN Institute for Nuclear Research
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-12765
• DOI: 10.1073/pnas.2404455121
• 发表日期: 2024-10-29
• 关键词: bell inequalities; VIOLATION; entanglement

摘要

Quantum mechanics imposes limits on the statistics of certain observables. Perhaps the most famous example is the uncertainty principle. Similar trade-offs also exist for the simultaneous violation of multiple Bell inequalities. In the simplest case of three observers, it has been shown that if two observers violate a Bell inequality, then none of them can violate any Bell inequality with the third observer, a property called monogamy of Bell violations. Forms of Bell monogamy have been linked to the nosignaling principle, and the inability of simultaneous violations of all inequalities is regarded as their fundamental property. Here, we show that the Bell monogamy does not hold universally and that in fact the only monogamous situation exists for only three observers. Consequently, the nature of quantum nonlocality is truly polygamous. We present a systematic methodology for identifying quantum states, measurements, and tight Bell inequalities that do not obey the monogamy principle for any number of more than three observers. The identified polygamous inequalities enable any subset of (N - 1) observers to reveal nonlocality, which is also shown experimentally by measuring Bell-type correlations of six-photon Dicke states. Our findings may be exploited for multiparty quantum key distribution as well as simultaneous self-testing of multiple nodes in quantum networks.