Contrast Interferometry with Quantum Degenerate Ytterbium Gases

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。实验将在实验室冷却到极低温度的原子气体上进行，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。如果不同的部分与光的相互作用不同，那么这就表现在重组BEC的性质上。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-物质相互作用的强度。他们的研究结果将为这一基本过程的潜在理论的可能改进提供信息。他们正在研究的原子（镱）在开发改进的全球定位系统（GPS）时间标准和开发量子计算机方面具有潜在的应用；这两项努力都涉及到该小组在这个项目中帮助推进的各种激光原子控制技术。参与该项目的学生将获得原子、激光和电子学实验方法的经验，并参与数据分析、建模以及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。由于单个光子的吸收，原子反冲的动能将被精确地测量为频率，通过进一步发展该小组演示的反差干涉测量技术与镱BECs。这种反冲频率与其他测量相结合，将准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是普遍存在的，QED理论扩展到各个物理子领域。持续改进是至关重要的。对比度干涉仪利用脉冲光驻波来分裂和重组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，该小组的干涉测量技术将推进BEC操作方法，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.