Tracking a trio of rubidium atoms Crossed molecular beams have provided decades' worth of knowledge into how quantum mechanics governs chemical reactivity. Nonetheless, the technique is generally limited to the collision of two partners. Wolf et al. report on a three-body process with full quantum state resolution. By cooling rubidium atoms to ultralow temperatures in an optical trap, they were able to observe dimer formation, stabilized by collision with a third atom, and extract the precise dependence of product states on the initial states of the atoms involved. Science, this issue p. 921 A three-atom collision leading to diatomic rubidium is elucidated quantum mechanically at ultracold temperature. Experimental investigation of chemical reactions with full quantum state resolution for all reactants and products has been a long-term challenge. Here we prepare an ultracold few-body quantum state of reactants and demonstrate state-to-state chemistry for the recombination of three spin-polarized ultracold rubidium (Rb) atoms to form a weakly bound Rb2 molecule. The measured product distribution covers about 90% of the final products, and we are able to discriminate between product states with a level splitting as small as 20 megahertz multiplied by Planck’s constant. Furthermore, we formulate propensity rules for the distribution of products, and we develop a theoretical model that predicts many of our experimental observations. The scheme can readily be adapted to other species and opens a door to detailed investigations of inelastic or reactive processes.

中文翻译：

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超冷铷气体中三体复合的状态间化学

跟踪三个铷原子 交叉分子束为量子力学如何控制化学反应提供了数十年的知识。尽管如此，该技术通常仅限于两个伙伴的碰撞。沃尔夫等人。报告具有完整量子态分辨率的三体过程。通过在光阱中将铷原子冷却到超低温，他们能够观察到二聚体的形成，通过与第三个原子的碰撞而稳定，并提取产物状态对所涉及原子的初始状态的精确依赖性。科学，这个问题 p。921 导致双原子铷的三原子碰撞在超低温下被量子力学地阐明。对所有反应物和产物进行全量子态分辨率的化学反应实验研究一直是一项长期挑战。在这里，我们制备了反应物的超冷少体量子态，并展示了三个自旋极化超冷铷 (Rb) 原子重组形成弱结合 Rb2 分子的状态到状态化学。测得的产品分布覆盖了大约 90% 的最终产品，我们能够通过小至 20 兆赫兹乘以普朗克常数的电平分裂来区分产品状态。此外，我们制定了产品分布的倾向规则，并开发了一个理论模型来预测我们的许多实验观察。