标题： 合成与宇宙轴子杂交：纠缠光子、(HBT)和量子拍现象 显示英文标题

标题： Synthetic and cosmological axion hybridization: entangled photons, (HBT) and quantum beats

摘要： 本文论证了合成轴子（拓扑绝缘体或外尔半金属中出现的集体激发）通过共同的双光子衰变通道与宇宙轴子（一个引人注目的暗物质候选者）发生杂化，因为它们都通过 Chern-Simons 项与电磁场耦合。 我们指出了一种类似于 V 型三能级系统的类比，其中两个上能级分别对应于合成轴子和宇宙轴子衰变为双光子态。 Weisskopf-Wigner 多能级原子自发衰变理论得到了补充和扩展，以描述杂化的动力学。 最终的双光子态既表现出运动动量和偏振纠缠，并且由于衰变路径之间的干涉而显示出量子拍现象。 初始状态下任意一种轴子的群体都会通过杂化诱导另一种轴子的群体。 因此，暗物质轴子凝聚体会诱导出合成轴子的凝聚体，尽管幅度很小。 我们获得了动量和偏振分辨的 Hanbury-Brown-Twiss (HBT) 二阶相干性，用于描述同时关联的双光子探测。 它显示出量子拍，频率由合成轴子和宇宙轴子能量差决定，并且可以通过\emph{或许可以被利用}探测任一类型的轴子激发。 当宇宙轴子的耦合趋于零时，可以得到单独的合成轴子情况，其特征是类似的双光子关联。 因此，二阶 (HBT) 双光子相干性\emph{可能}提供了另一种检测新兴凝聚态轴子集体激发的机制。 文中还讨论了与参数下转换光子的相似性和差异性。 显示英文摘要

摘要： In this article it is argued that synthetic axions, emergent collective excitations in topological insulators or Weyl semimetals hybridize with the cosmological axion, a compelling dark matter candidate via a common two photon decay channel since they both couple to electromagnetic fields via a Chern-Simons term. We point out an analogy to a V-type three level system with the two upper levels identified with the synthetic and cosmological axions decaying into a two-photon state. The Weisskopf-Wigner theory of spontaneous decay in multi level atoms is complemented and extended to describe the dynamics of hybridization. The final two-photon state features both kinematic and polarization entanglement and displays quantum beats as a consequence of the interference between the decay paths. An initial population of either axion induces a population of the other via hybridization. Consequently, a dark matter axion condensate induces a condensate of the synthetic axion, albeit with small amplitude. We obtain a momentum and polarization resolved Hanbury- Brown Twiss (HBT) second order coherence describing coincident correlated two-photon detection. It exhibits quantum beats with a frequency given by the difference between the energies of the synthetic and cosmological axion and \emph{perhaps may be harnessed} to detect either type of axion excitations. The case of synthetic axions individually is obtained in the limit of vanishing coupling of the cosmological axion and features similar two-photon correlations. Hence second order (HBT) two-photon coherence \emph{may} provide an alternative detection mechanism for emergent condensed matter axionic collective excitations. Similarities and differences with parametrically down converted photons are discussed.