近日，美国密歇根大学的P. R. Berman与A. Kuzmich合作并取得一项新进展。经过不懈努力，他们提出原子阵列级联相关发射理论。相关研究成果已于2024年5月16日在国际知名学术期刊《物理评论A》上发表。
该研究团队提出了N个固定的“三能级”原子阵列的级联发射理论。每个原子的基态总角动量为J=0，中间态总角动量为J=1，高能态总角动量为J=0。原子在基态和高能态的空间相叠加中制备，集体共享单个激发。研究人员计算了在每个跃迁上以给定极化，向给定方向发射的辐射的时间积分联合概率分布，并使用该联合概率分布来计算每个跃迁上发射的时间积分强度。
考虑到原子间的偶极-偶极相互作用。他们得到了两个原子的解析表达式，并将计算形式推广到任意位置N个原子的系综。正如预期的那样，在高能跃迁上发射的辐射是非极化的和各向同性的。
然而，有些令人惊讶的是，研究人员发现，对于对向传播场激发和几乎相等的中、中-高能级跃迁频率，在低能级跃迁上的辐射也是各向同性和非极化的，只要原子是在完全对称状态下制备的。他们还建立了在高低能跃迁的特定方向上，可以有相位匹配增强联合概率密度的条件。
附：英文原文
Title: Theory of cascade correlated emission from atom arrays
Author: P. R. Berman, A. Kuzmich
Issue&Volume: 2024/05/16
Abstract: We present a theory of cascade emission from an array of N fixed, “three-level” atoms. The total angular momentum of the ground state of each atom is J=0, that of the intermediate state is J=1, and that of the upper state is J=0. The atoms are prepared in a spatially phased superposition of their ground and upper states, collectively sharing a single excitation. We calculate the time-integrated, joint probability distribution for radiation to be emitted in a given direction with a given polarization on each transition and use this joint probability distribution to calculate the time-integrated intensity emitted on each transition. The dipole-dipole interaction between the atoms is taken into account. Analytic expressions are obtained for two atoms and the calculation is then extended formally to an ensemble of N atoms at arbitrary positions. As expected, the radiation emitted on the upper transition is unpolarized and isotropic. However, somewhat surprisingly, we find that for excitation by counterpropagating fields and for nearly equal ground to intermediate and intermediate to upper level transition frequencies, the radiation on the lower transition is also isotropic and unpolarized, provided the atoms are prepared in a fully symmetric state. We also establish conditions for which there can be a phase-matched enhancement of the joint probability density for specific directions of emissions on the upper and lower transitions.
DOI: 10.1103/PhysRevA.109.053714
Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.109.053714
