Instituto de Física de São Carlos, Universidade de São Paulo, São Paulo, Brasil.
Phys Rev Lett. 2012 Jun 22;108(25):253004. doi: 10.1103/PhysRevLett.108.253004. Epub 2012 Jun 19.
Two-photon cooperative absorption is common in solid-state physics. In a sample of trapped cold atoms, this effect may open up new possibilities for the study of nonlinear effects. The experiment described herein starts with two colliding Na atoms in the S hyperfine ground state. The pair absorb two photons, resulting in both a P(1/2) and a P(3/2) atom. This excitation is observed by ionization using an external light source. A simple model that considers only dipole-dipole interactions between the atoms allows us to understand the basic features observed in the experimental results. Both the pair of generated atoms and the photons originating from their decay are correlated and may have interesting applications that remain to be explored.
双光子协同吸收在固态物理学中很常见。在囚禁冷原子的样本中，这种效应可能为研究非线性效应开辟新的可能性。本文所描述的实验始于两个处于 S 超精细基态的碰撞 Na 原子。这对原子吸收两个光子，导致同时产生一个 P(1/2)和一个 P(3/2)原子。这种激发可以通过使用外部光源进行电离来观察。一个仅考虑原子之间偶极-偶极相互作用的简单模型使我们能够理解实验结果中观察到的基本特征。生成的原子对和源自它们衰变的光子都是相关的，可能具有有趣的应用，有待进一步探索。
