Contrast Interferometry with Quantum Degenerate Ytterbium Gases

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。实验将在实验室中冷却到非常低的温度的原子气体上进行，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。就像激光束一样，BEC可以分裂成多个部分，然后重新组合。如果不同的部分与光的相互作用不同，那么这就表现在重新组合的BEC的特性中。通过使用光脉冲分裂，重组，然后观察BEC，该小组将精确测量光与物质相互作用的强度。他们的结果将提供有关这一基本过程的基础理论的可能改进的信息。 他们正在研究的原子（镱）在改进全球定位系统（GPS）的时间标准和量子计算机的开发方面具有潜在的应用;这两项工作都涉及该小组正在帮助推进的激光原子控制技术。从事该项目的学生将获得涉及原子，激光和电子的实验方法的经验，并参与数据分析，建模，并将实验结果与理论联系起来。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。通过进一步开发该小组展示的镱BEC对比度干涉测量技术，将精确测量由于吸收单个光子而反冲的原子的动能作为频率。这个反冲频率，结合其他测量，将精确地确定精细结构常数α，并测试量子电动力学（QED）理论。精细结构常数在自然界中普遍存在，QED理论扩展到各个物理子领域。 继续改进具有根本重要性。对比度干涉仪利用脉冲光学驻波来分离和重组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，该小组的干涉测量技术将推进BEC操纵方法，并将用于研究多体现象，如BEC相变。

This grant will support a project to sensitively measure the interaction between light and matter. The experiments will be performed on an atomic gas 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. If the different parts interact differently with light, then this shows up in the properties of the recombined BEC. By using light pulses to split, recombine, and then observe BECs, the group will precisely measure the strength of the light-matter interaction. Their results will provide information regarding possible refinements of the underlying theory of this fundamental process. The atom they are studying (Ytterbium) has potential applications in the development of improved time standards for the global positioning system (GPS) and in the development of quantum computers; both of these efforts involve the sorts of laser-atom control techniques that the group is helping to advance in this project. The students working on the project will gain experience in experimental methods involving atoms, lasers, and electronics, and also be involved in data analysis, modeling, and connecting experimental results with theory. This will form good preparation for them to join the work force in academics 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, by further development of the group's demonstrated contrast interferometry technique with ytterbium BECs. This recoil frequency, combined with other measurements, will accurately determine the fine structure constant alpha, and test the theory of quantum electrodynamics (QED). The fine structure constant is ubiquitous in nature, and QED theory extends across various physics sub-fields. Continued refinement is of fundamental importance. The contrast interferometer utilizes pulsed optical standing waves to split 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, the group's interferometry technique will advance BEC manipulation methods, and will be used to study many-body phenomena, such as the BEC phase transition.