标题： 大自旋极限下宏观实在性量子违背的条件 显示英文标题

标题： Conditions for Quantum Violation of Macrorealism in Large-spin Limit

摘要： 本研究探讨了如何从具有反直觉特性的量子基础中产生经典的宏观行为。 通过熵的Leggett-Garg不等式来衡量量子系统时间关联性偏离经典观点的程度。 我们引入了一个几何框架以推导涉及高阶关联的熵的Leggett-Garg不等式，并利用WKB近似分析大自旋系统中的渐近行为。 结果显示，对于完全混合态，在宏观极限下，量子违反收敛到一个常数，而不是随着系统的熵以对数增长，表明随着能量级数量的增加，宏观实在论越来越占据主导地位。 然而，在某些参数设置下会出现例外情况，其中半经典近似完全失效，使得不等式表现出最大量子违反，从而揭示了即使在宏观尺度上，量子和经典描述仍然不相容。 值得注意的是，这种违反仅来源于单个系统的时序关联，这与在诸如超导体等多体系统中观察到的宏观量子现象有本质区别。 显示英文摘要

摘要： This study investigates how macroscopic classical behavior emerges from a quantum underpinning with counterintuitive characteristics. The deviation from classical standpoint of a quantum system's temporal correlations is measured via the entropic Leggett-Garg inequality. We introduce a geometric framework to derive entropic Leggett-Garg inequalities involving higher-order correlations, and analyze their asymptotic behavior in large-spin systems by employing the WKB approximation. Results show that, for maximally mixed states, quantum violations converge to a constant in the macroscopic limit, rather than growing logarithmically with the system's entropy, indicating that macroscopic realism increasingly dominates as the number of energy levels expands. However, exceptions arise with certain parameter settings, where the semiclassical approximation breaks down entirely, enabling inequalities to exhibit maximal quantum violation, thus revealing that quantum and classical descriptions remain incompatible even on a macroscopic scale. It is noteworthy this violation originates exclusively from the temporal correlations of a single system, distinguishing it from macroscopic quantum phenomena observed in many-body systems such as superconductivity.