Measuring Attometer-Scale Thermal Fluctuations in Optical Coatings for Applications in Gravitational Wave Detection

随着高级激光干涉引力波天文台（LIGO）对引力波（GW）的探测，打开了一扇通往宇宙的新窗口。这些第一次探测只是标志着一个过程的开始，使LIGO更敏感，增加探测率与每一步沿着。LIGO降噪中最重要的公开问题之一与干涉仪中使用的反射镜的涂层有关。精密光学测量技术的进步使得测量宏观材料的热涨落成为可能。机械系统中发生在阿托米尺度上的热波动，被称为“热噪声”，是引力波探测器和最佳频率参考中的限制噪声源。 这项工作将扩大麻省理工学院正在进行的实验的范围，该实验用于测量先进LIGO反射镜的热噪声。 新的范围将包括表征目前用于引力波探测器的涂层的潜在替代品。该奖项支持的实验的基本原理是谐振腔的不同空间模式所经历的热噪声很容易与大多数技术噪声分离，从而使桌面实验中的高信噪比测量成为可能。这些研究将测试用于离子束溅射（IBS）涂层的新材料，寻找新的有前途的候选材料来取代LIGO目前使用的涂层。涂层热噪声领域的研究将使我们能够扩展引力波探测器的范围，制造更精确的时钟，并更深入地探索光-机相互作用的量子本质。 由于拟议的工作将对未来引力波探测器的设计产生重大影响，因此其紧迫性不能被夸大。

With the detection of Gravitational Waves (GW) by the Advanced Laser Interferometric Gravitational-Wave Observatory (LIGO) a new window to the Universe has been opened. These first detections only mark the beginning of a process to make LIGO more sensitive, increasing the detection rate with each step along the way. One of the most important open problems in LIGO noise reduction is related to the coatings of the mirrors used in the interferometer. Advances in precision optical measurement have made it possible to measure the thermal fluctuations of macroscopic materials. Thermal fluctuations in mechanical systems which occur at the atto-meter scale, and are known as "thermal noise", are a limiting noise source in gravitational wave detectors and in the best frequency references. This work will expand the scope of an ongoing experiment at MIT which was used to measure the thermal noise of Advanced LIGO mirrors. The new scope will include characterizing potential replacements for the coatings currently used in gravitational wave detectors.The founding principle of the experiments supported by this award is that the thermal noise experienced by different spatial modes of a resonant cavity is easily separated from most technical noises, making a high signal to noise measurement possible in a tabletop experiment. These studies will test new materials used for ion-beam-sputtered (IBS) coatings, searching for new promising candidates to replace the coatings currently used by LIGO. Research in the area of coating thermal noise will allow us to extend the reach of gravitational wave detectors, make more precise clocks, and probe more deeply the quantum nature of opto-mechanical interactions. Since the proposed work will have a strong influence on the design of future gravitational wave detectors, its urgency cannot be overstated.