Precision Measurements with Complex Atoms

该项目的目标是对自然界的基本对称性进行沿着实验研究：（1）测量镱中的原子宇称破坏（APV），（2）寻找镝中精细结构“常数”α和APV的时空变化，（3）在钡中进行离散对称性测试。这三台仪器的位置很好，可以在一系列同位素（镱、镝、钡）上进行APV测量，产生有关中子半径如何变化的信息，以及超新星、中子星和重元素的产生。这些实验提供了一个了解原子核内弱相互作用的独特窗口。我们目前对自然规律的理解主要基于对称性和不变性的概念。例如，我们通常假设物理学的基本定律不随时间而改变。然而，自然界的许多对称性都被打破了，例如，现实世界与其镜像之间的对称性（所谓的左右不对称，也称为对称性）。奇偶性违反）。虽然高能对撞机实验和天文观测为基本对称性的研究提供了强大的实验室，但像本项目中的小规模桌面实验可以在某些领域与其他技术竞争。此外，它们还能够提供通过其他手段难以获得的独特科学信息。这种小规模的实验是培养新一代动手科学家的理想选择。

The project aims at table-top experimental investigation of fundamental symmetries of nature along three thrusts: (1) measuring atomic parity violation (APV) in ytterbium, (2) searching for spatio-temporal variation of the fine-structure "constant" alpha and APV in dysprosium, and (3) conducting discrete symmetry tests in barium. The three apparatus are well-positioned to perform APV measurements across a chain of isotopes (Ytterbium, Dysprosium, Barium), yielding information about how the neutron radius varies, with ramifications to supernovas, neutron stars, and the creation of heavy elements. These experiments provide a unique window into weak interactions within atomic nuclei.Our present understanding of the laws of Nature is largely based on the concepts of symmetry and invariance. For example, we generally assume that fundamental laws of physics do not change with time. Many symmetries of nature, however, are broken, for example, the symmetry between the actual world and its mirror image (the so-called left-right asymmetry a.k.a. parity violation). While experiments with high-energy colliders and astronomical observations provide powerful laboratories for the study of fundamental symmetries, small-scale table-top experiments such as the ones in this project can be competitive with other techniques in certain areas. Moreover, they are also capable of providing unique scientific information that is difficult to obtain by other means. Such small-scale experiments are ideal for training the new generation of hands-on scientists.