Optomechanics for Quantum Noise Reduction in Gravitational Wave Detectors

2015年，LIGO探测器直接探测到合并双黑洞系统发出的引力波，标志着引力波天文学的开始。从一个合并的双中子星系统中探测到的引力波与伽马射线爆发同时发生，再加上传统望远镜的后续观测，证明了多信使天文学的力量及其潜力。为了继续取得这些发现，必须改进现有引力波天文台的灵敏度，并且必须发展使下一代探测器成为可能的物理学。一旦达到设计灵敏度，用于测量引力波的激光场的量子涨落将限制高级LIGO在其大部分频率带宽内的灵敏度。这个项目的重点是通过利用光与机械运动的耦合来减少量子噪声的限制。这个项目结合了几个关键组件，将使下一代探测器成为可能。光学实验将使用质量在100纳克左右的微制造机械谐振器进行。具体来说，该小组将研究光力学腔中的非经典或压缩光态的相互作用，该腔受到辐射压力和宽频带中的散粒噪声的限制，正如Advanced LIGO预计的那样，一旦达到设计灵敏度。为了实现这一目标，AlGaAs反射镜将被低温冷却并放置在高精细度的光学腔中。低温操作将使标准量子极限接近，甚至超越。在这种灵敏度下，这些器件是在滤光腔中使用光力学相互作用的良好候选者。光机械滤光腔控制辐射压力和系统的机械自由度之间的耦合，从而在光通过滤光腔时产生一定的效应。原则上，这些滤光腔可用于调节光的压缩状态，以产生适合注入引力波干涉仪的频率依赖性。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The direct detection of gravitational waves emitted by a coalescing binary black hole system by the LIGO detectors in 2015 marked the beginning of gravitational wave astronomy. The detection of gravitational waves from a coalescing binary neutron star system coincident with a gamma ray burst, with follow-up observations by traditional telescopes, demonstrated the power of multimessenger astronomy and the potential it holds. To continue making these discoveries, improvements to the sensitivity of existing gravitational wave observatories must be made, and the physics that will make the next generation of detectors possible must be developed. Quantum fluctuations of the laser fields used to measure gravitational waves will limit Advanced LIGO's sensitivity across most of its frequency bandwidth once it reaches design sensitivity. This project is focused on reducing the limitation of that quantum noise by exploiting the coupling of light to mechanical motion.This project combines several of the key components that will make the next generation of detectors possible. Optical experiments will be conducted with microfabricated mechanical resonators with masses on the order of 100 nanograms. Specifically, the group will study the interaction of non-classical, or squeezed, states of light in an optomechanical cavity that is limited by both radiation pressure and shot noise in a broad frequency bandwidth, as Advanced LIGO is expected to be once it reaches design sensitivity. In order to achieve this goal, AlGaAs mirrors will be cryogenically cooled and placed in a high finesse optical cavity. Cryogenic operation will allow the Standard Quantum Limit to be approached, or even surpassed. At that sensitivity, these devices are good candidates for employing optomechanical interactions in filter cavities. Optomechanical filter cavities manipulate the coupling between radiation pressure and the mechanical degrees of freedom of the system to produce certain effects in light passing through the cavity. In principle, these filter cavities may be used to condition squeezed states of light to produce a frequency dependence suitable for injection to gravitational wave interferometers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.