CAREER: Atom Interferometry Experiments in Fundamental Physics

这项CAREER奖支持的研究正在探索使用原子干涉测量法对物理学基本定律进行精确测试的新方法。原子干涉仪利用量子力学的波粒二象性。原子（例如，铯）物质波被分裂并沿沿着两条路径发送。当两个波相互干涉时，探测到原子的概率由物质波的相位差给出。原子干涉仪的高灵敏度源于这样一个事实，即相位差可以是数百万弧度，而弧度的微小部分会导致检测概率的可测量变化。正在为这项研究建造的仪器使用铯和锂原子。他们使用“大动量转移”，这是一种新方法，可以实现物质波路径的大分离，从而提高灵敏度。作为本研究的一部分，这种方法得到了进一步的改进。这些仪器被应用于基础物理学中一个令人兴奋的研究议程：测量表征电磁相互作用强度的基本常数，称为精细结构常数，从而高精度地测试量子电动力学理论;验证引力必须服从爱因斯坦广义相对论定律的概念，例如引力不知道优先方向的事实;并测试自由落体的普遍性，这是爱因斯坦等效原理的基本组成部分之一，广义相对论的所有内容都来自于此。本科生、研究生和博士后都参与其中，因此这项研究有助于培养下一代科学家和工程师。PI指出，深入参与研究往往开始于学生职业生涯的后期阶段。因此，PI寻求增加本科生的参与，事实上，用于本研究的干涉仪之一主要是由本科生建立的。

Research supported by this CAREER award is exploring new ways to use atom interferometry to perform precision tests of fundamental laws of physics. An atom interferometer uses the wave-particle duality of quantum mechanics. An atomic (e.g., cesium) matter wave is split and sent along two paths. When the two waves are interfered, the probability of detecting the atom is given by the phase difference of the matter waves. The high sensitivity of atom interferometers derives from the fact that the phase difference can be millions of radians, whereas tiny fractions of radians lead to a measurable change in the detection probability. The instruments being constructed for this research use cesium and lithium atoms. They use "large momentum transfer," a new method that allows attaining a large separation of the matter wave's paths, thus increasing sensitivity. This method is further improved as part of this research.The instruments are applied to pursue an exciting research agenda in fundamental physics: Measuring a fundamental constant that characterizes the strength of the electromagnetic interaction, known as the fine structure constant, and thereby testing the theory of quantum electrodynamics to high precision; testing the notion that the force of gravitation must obey the laws of Einstein's theory of General Relativity, such as the fact that gravity knows no preferred direction; and testing the universality of free fall, one of the fundamental ingredients of the Einstein Equivalence Principle, from which all of General Relativity follows. Undergraduate students, graduate students, and postdocs take part, so this research helps training the next generation of scientists and engineers. The PI has noted that deep involvement in research often starts at a rather late stage of the student's career. The PI therefore seeks to increase the participation of undergraduate students, and in fact one of the interferometers used for this research has been set up mainly by an undergraduate student.