Reducing Coating Thermal Noise in Gravitational Wave Detectors

近50年来，直接探测引力波一直是重力和天体物理学研究的主要挑战。成功探测到引力波有望提供关于中子星、超新星爆炸、黑洞以及大爆炸后最初时刻的洞察和信息，这些是电磁望远镜无法获得的。它还将为爱因斯坦的广义相对论提供一个实验测试，这可以帮助确定我们对引力和宇宙学的理解是否还有缺失的元素。探测天文引力波需要极其精确的光学测量。光学涂层热噪声是第二代引力波探测器最敏感频段的限制性噪声源。本项目是通过测量光学涂层材料的机械损耗来研究和改进涂层热噪声。测量涂层材料中的两个耗散源（大块和扭转运动）可以为低热噪声涂层设计提供有价值的信息，并深入了解涂层材料中热噪声的原因。涂层热噪声的改进将有引力波探测以外的应用。频率稳定、量子力学实验和其他精密光学应用都遇到了与引力波探测相同的涂层热噪声限制。其中一些具有商业和工业应用，特别是频率稳定和精确定时。此外，该提案有助于在美国大学建立一个实验物理项目，其中将包括本科生研究人员。这将有助于让美国学生（其中许多人渴望从事公共政策方面的职业）接触到实验科学和前沿研究。

Direct detection of gravitational waves has been a major challenge in gravity and astrophysics research for nearly 50 years. Successful detection of gravitational waves is expected to provide insight and information on neutron stars, supernova explosions, black holes, and the earliest moments after the Big Bang that is not available to electromagnetic telescopes. It will also provide an experimental test of Einstein's General Theory of Relativity which can help determine if there are missing elements to our understanding of gravity and cosmology. The detection of astronomical gravitational waves requires extremely precise optical measurements. Coating thermal noise in the optics is a limiting noise source in the most sensitive frequency band of second generation gravitational wave detectors. This project is on the study and improvement of coating thermal noise through novel measurements of the mechanical loss in optical coating materials. Measuring two sources of dissipation (from bulk and torsional motion) in coating materials can give valuable information for low thermal noise coating design as well as insights into the causes of thermal noise in coating materials.Improvements in coating thermal noise will have applications beyond gravitational wave detection. Frequency stabilization, quantum mechanics experiments, and other precision optics applications are encountering the same coating thermal noise limitation as gravitational wave detection. Some of these have commercial and industrial applications, especially frequency stabilization and precision timing. In addition, this proposal helps to develop an experimental physics program at American University that will include undergraduate researchers. This will help expose American students (many of whom aspire to careers in public policy) to experimental science and cutting edge research.