Precision Measurements with Complex Atoms

该项目旨在通过三个推力对自然界基本对称性进行桌面实验研究：(1)测量镱的原子宇称违和（APV），(2)寻找镝的精细结构“常数”α和APV的时空变化，(3)进行钡的离散对称性测试。这三台仪器的位置很好，可以对一系列同位素（钇、镝、钡）进行APV测量，从而获得中子半径如何变化的信息，以及超新星、中子星和重元素产生的影响。这些实验为研究原子核内的弱相互作用提供了一个独特的窗口。我们目前对自然规律的理解很大程度上是基于对称和不变性的概念。例如，我们通常假设物理的基本定律不随时间而改变。然而，自然界的许多对称性被打破了，例如，现实世界与其镜像之间的对称性（所谓的左右不对称，又称宇称破坏）。虽然高能对撞机实验和天文观测为研究基本对称性提供了强大的实验室，但在某些领域，像这个项目中的小规模桌面实验可以与其他技术竞争。此外，它们还能够提供难以通过其他方式获得的独特科学信息。这种小规模的实验是训练新一代动手能力强的科学家的理想选择。

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.