Precision Contrast Interferometry with Ytterbium Bose-Einstein Condensates

这笔赠款将支持一个项目，以灵敏地测量光和物质之间的相互作用。 通过监测由于吸收或发射光而引起的原子速度变化，该团队将测量一个被称为精细结构常数的基本自然常数。这些实验将使用在实验室中冷却到非常低温度的原子气体进行，此时它会转变为一种称为玻色-爱因斯坦凝聚体（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，以制造原子的干涉仪。 通过观察BEC干涉条纹，该团队将精确测量原子因吸收或发射光量子（光子）而产生的速度变化。结果将提供有关可能的改进量子力学的基本理论，描述这一基本过程的信息。 从事这个项目的学生将获得激光，电子和原子物理研究的经验。 学生还将获得分析数据，建模复杂系统，并将实验结果与理论相结合的经验。这将为他们加入学术界和工业界的劳动力队伍，成为下一代科学家和工程师的一部分做好准备。 由于吸收单个光子而反冲的原子的动能将被精确地测量为频率。 这将使用对比度干涉测量技术与镱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理论延伸到整个物理学的许多子领域。提高精细结构常数的精确度和QED测试的精度都是至关重要的。对比度干涉仪利用脉冲光学驻波来分裂、操纵和重组BEC。干涉仪信号通过经由光学行波的反射监测所得干涉图案的对比度来获得。除了测试QED，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.