Passante Roberto, Rizzuto Lucia
Dipartimento di Fisica e Chimica-Emilio Segrè, Università degli Studi di Palermo, Via Archirafi 36, I-90123 Palermo, Italy.
Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, I-95123 Catania, Italy.
Entropy (Basel). 2023 Oct 8;25(10):1424. doi: 10.3390/e25101424.
In this review, we investigate several aspects and features of spatial field correlations for the massless scalar field and the electromagnetic field, both in stationary and nonstationary conditions, and show how they manifest in two- and many-body static and dynamic dispersion interactions (van der Waals and Casimir-Polder). We initially analyze the spatial field correlations for noninteracting fields, stressing their nonlocal behavior, and their relation to two-body dispersion interactions. We then consider how field correlations are modified by the presence of a field source, such as an atom or in general a polarizable body, firstly in a stationary condition and then in a dynamical condition, starting from a nonstationary state. We first evaluate the spatial field correlation for the electric field in the stationary case, in the presence of a ground-state or excited-state atom, and then we consider its time evolution in the case of an initially nonstationary state. We discuss in detail their nonlocal features, in both stationary and nonstationary conditions. We then explicitly show how the nonlocality of field correlations can manifest itself in van der Waals and Casimir-Polder interactions between atoms, both in static and dynamic situations. We discuss how this can allow us to indirectly probe the existence and the properties of nonlocal vacuum field correlations of the electromagnetic field, a research subject of strong actual interest, also in consequence of recent measurements of spatial field correlations exploiting electro-optical sampling techniques. The subtle and intriguing relation between nonlocality and causality is also discussed.
在本综述中，我们研究了静止和非静止条件下无质量标量场和电磁场的空间场相关性的几个方面和特征，并展示了它们如何在两体和多体静态及动态色散相互作用（范德瓦尔斯相互作用和卡西米尔 - 波尔德相互作用）中体现。我们首先分析非相互作用场的空间场相关性，强调其非局域行为以及与两体色散相互作用的关系。然后我们考虑场源（如原子或一般的可极化体）的存在如何改变场相关性，首先是在静止条件下，然后是在动态条件下，从非静止状态开始。我们首先评估在存在基态或激发态原子的静止情况下电场的空间场相关性，然后考虑在初始非静止状态下其时间演化。我们详细讨论了它们在静止和非静止条件下的非局域特征。然后我们明确展示了场相关性的非局域性如何在原子间的范德瓦尔斯相互作用和卡西米尔 - 波尔德相互作用中，在静态和动态情况下体现出来。我们讨论了这如何使我们能够间接探测电磁场非局域真空场相关性的存在及其性质，这是一个当前具有强烈实际意义的研究课题，也是由于最近利用电光采样技术对空间场相关性进行的测量。我们还讨论了非局域性与因果性之间微妙而有趣的关系。
