美国哈佛大学Kang-Kuen Ni团队实现了态间超冷化学统计动力学的精准测试。相关研究成果于2021年5月19日发表在国际顶尖学术期刊《自然》。

化学反应是一类量子问题，对当前的理论理解和计算能力都提出了挑战。在超低温下发生的反应为量子化学和散射理论提供了一个理想的试验场，因为它们可以用前所未有的控制进行实验研究，同时能显示出高度复杂的动力学。

该文中，研究人员报告了2KRb→K2 + Rb2反应的全生成物态分布。反应物的超冷制备使研究人员能够完全控制它们的初始量子自由度，而两种产物的状态分辨和一致性检测使它们散射到57种允许的转动态对中的每一种的概率得以测量。研究结果与基于统计理论的状态计数模型完全一致，但也揭示了一些偏离状态对。特别是，研究人员观察到，在最接近外能极限的态对中，由于长程势抑制了产物的逃逸而导致强烈的种群抑制。

该研究测量的完整性为量子动力学计算提供了一个超越当前技术水平的基准。

附：英文原文

Title: Precision test of statistical dynamics with state-to-state ultracold chemistry

Author: Yu Liu, Ming-Guang Hu, Matthew A. Nichols, Dongzheng Yang, Daiqian Xie, Hua Guo, Kang-Kuen Ni

Issue&Volume: 2021-05-19

Abstract: Chemical reactions represent a class of quantum problems that challenge both the current theoretical understanding and computational capabilities1. Reactions that occur at ultralow temperatures provide an ideal testing ground for quantum chemistry and scattering theories, because they can be experimentally studied with unprecedented control2, yet display dynamics that are highly complex3. Here we report the full product state distribution for the reaction 2KRb → K2 + Rb2. Ultracold preparation of the reactants allows us complete control over their initial quantum degrees of freedom, whereas state-resolved, coincident detection of both products enables the probability of scattering into each of the 57 allowed rotational state-pairs to be measured. Our results show an overall agreement with a state-counting model based on statistical theory4,5,6, but also reveal several deviating state-pairs. In particular, we observe a strong suppression of population in the state-pair closest to the exoergicity limit as a result of the long-range potential inhibiting the escape of products. The completeness of our measurements provides a benchmark for quantum dynamics calculations beyond the current state of the art.

DOI: 10.1038/s41586-021-03459-6

Source: https://www.nature.com/articles/s41586-021-03459-6