Quantum Optomechanics at the Standard Quantum Limit

该奖项支持相对论和相对论天体物理学的研究，它解决了NSF“宇宙之窗”大构想的优先领域。直接探测引力波（GW）是几十年来在物理学和实验专业知识的发展下才得以实现的，这些专业知识需要用来建造探测引力波的干涉仪。现在，GW探测器的灵敏度受到了量子噪声的限制，这些量子噪声的形式与探测到的光子数量的计数误差有关，以及辐射压力噪声形式的反作用。本项目将在低温系统中使用微机械镜像振荡器的原型系统中探索这些量子噪声的相互作用。该项目将探索在小型系统中减轻这些噪声影响的技术，以便将来将其应用于大型GW探测器。该奖项将支持和指导学生，并鼓励来自非传统背景和传统上代表性不足群体的参与者。通过研究讲座、公开讲座和实验室参观，研究参与者在传播令人兴奋的物理研究方面发挥了重要作用，包括在量子力学和GWs领域。标准量子极限（SQL）限制任何连续位置测量，其中测量不精度（射噪声）与量子反作用力（辐射压力噪声）不相关。原则上，通过将这两种噪声关联起来，SQL可能会被破坏。在拟议的研究中，这将通过在一个失谐腔中使用光学弹簧效应和一个可移动的50纳克反射镜来实验证明。该系统以前用于在室温下观察量子反作用，这里将被冷却到20开尔文以达到所需的灵敏度。我们还将探讨超越SQL的其他方法，包括变分读出。这些实验结果将为未来GW探测器的设计提供参考。布朗热噪声低于SQL的微镜振荡器也是不稳定光机械滤光腔的候选者。该项目还将开发测量SQL以下水平的热噪声的技术。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。

This award supports research in relativity and relativistic astrophysics, and it addresses the priority areas of NSF's "Windows on the Universe" Big Idea. The direct detection of gravitational waves (GW) was made possible by decades of work developing the physics and experimental expertise needed to construct the interferometers that made the detections. GW detectors are now limited in their sensitivity by quantum noise in the forms of shot noise, associated with counting error in the number of photons detected, and backaction in the form of radiation pressure noise. This project will explore the interplay of these quantum noises in a prototype system that uses micromechanical mirror oscillators in a cryogenic system. The project will explore techniques to mitigate the effects of these noises in a small system so that they may be applied to large GW detectors in the future. The award will support and mentor students and encourage participants from non-traditional backgrounds and traditionally underrepresented groups. Participants in the research play a strong role in disseminating exciting physics research, including in the areas of quantum mechanics and GWs, through research talks, public talks, and lab tours.The Standard Quantum Limit (SQL) limits any continuous position measurement in which the measurement imprecision (shot noise) is uncorrelated with the quantum backaction (radiation pressure noise). The SQL may be breached, in principle, by correlating the two noises. In the proposed research, this will be experimentally demonstrated by using the optical spring effect in a detuned cavity with a movable 50 nanogram mirror. This system was previously used to observe quantum backaction at room temperature, and here will be cooled to 20 degrees Kelvin to reach the required sensitivity. Other methods to surpass the SQL, including the variational readout, will also be explored. The results of these experiments will inform the design of future GW detectors. The micromirror oscillators, with Brownian thermal noise below the SQL, are also candidates for unstable optomechanical filter cavities. The project will also develop techniques to measure the thermal noise at a level below the SQL.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.