Precision Contrast Interferometry with Ytterbium Bose-Einstein Condensates

这笔拨款将支持一个灵敏地测量光与物质之间相互作用的项目。通过监测原子因吸收或发射光而导致的速度变化，该团队将测量一个被称为精细结构常数的自然基本常数。实验将在实验室中将原子气体冷却到非常低的温度，此时它会转变成一种称为玻色-爱因斯坦凝聚物（BEC）的奇异状态。像激光束一样，BEC可以分裂成多个部分，然后重新组合，制成原子干涉仪。通过观察BEC干涉条纹，该团队将精确测量原子由于吸收或发射光量子（光子）而产生的速度变化。这些结果将为描述这一基本过程的量子力学基础理论的可能改进提供信息。参与该项目的学生将获得激光、电子学和原子物理研究方面的经验。学生还将获得分析数据、模拟复杂系统以及将实验结果与理论联系起来的经验。这将为他们加入学术界和工业界的工作队伍，成为下一代科学家和工程师的一部分做好充分的准备。原子因吸收单个光子而反冲的动能将被精确地测量为频率。这将使用反差干涉测量技术与镱BEC干涉仪。这个反冲频率，结合其他测量，将被用来精确地确定精细结构常数，并测试量子电动力学（QED）理论。精细结构常数在自然界中无处不在，QED理论在整个物理学中延伸到许多子领域。提高精细结构常数的已知精度和QED的测试精度都是至关重要的。对比度干涉仪利用脉冲光驻波来分裂、操纵和重组bec。干涉仪信号是通过监测光行波反射产生的干涉图样的对比度而获得的。除了测试QED外，该项目还将推进BEC的制备、操作和探测方法。

This grant will support a project to sensitively measure the interaction between light and matter. By monitoring the change in velocity for atoms due to absorbing or emitting light, this team will measure a fundamental constant of nature known as the fine structure constant. The experiments will be performed with an atomic gas that is cooled to very low temperatures in the laboratory, at which point it transforms into an exotic state called a Bose-Einstein condensate (BEC). Like a laser beam, the BEC can be split into multiple parts and then recombined, to make an interferometer for atoms. By observing BEC interference fringes, this team will precisely measure the velocity change for atoms due to absorbing or emitting light quanta (photons). The results will provide information regarding possible refinements to the underlying theory of quantum mechanics that describes this fundamental process. The students working on this project will gain experience with lasers, electronics, and atomic physics research. The students will also gain experience analyzing data, modeling complex systems, and connecting experimental results with theory. This will form good preparation for them to join the work force in academia and industry as part of the next generation of scientists and engineers. The kinetic energy of an atom recoiling due to absorption of a single photon will be precisely measured as a frequency. This will be done using the contrast interferometry technique with a ytterbium BEC interferometer. This recoil frequency, combined with other measurements, will be used to accurately determine the fine structure constant, and to test the theory of quantum electrodynamics (QED). The fine structure constant is ubiquitous in nature, and QED theory extends across many sub-fields throughout physics. Improving the accuracy with which the fine structure constant is known and the precision with which QED is tested are both of fundamental importance. The contrast interferometer utilizes pulsed optical standing waves to split, manipulate, and recombine BECs. The interferometer signal is obtained by monitoring the contrast of the resultant interference pattern via reflection of an optical traveling wave. In addition to testing QED, this project will also advance BEC preparation, manipulation, and probing methods.