CAREER: Cryogenic Interferometers in the Quantum Regime for Gravitational-Wave Science

该奖项支持桌面实验，以研究减轻引力波干涉仪中量子噪声的方法。在低噪声低温环境下，建立了受辐射压力和弹丸噪声双重限制的实验装置。为了在小规模原型中实现这一点，微制造的机械谐振器（约100纳克）将用作低振动低温恒温器内高精细光学腔的一面镜子，冷却到10K以下。随后将进行一系列实验来验证量子噪声模型，并测试降低量子噪声的方法。具体来说，一个纯差探测器将用于执行谐振器位置的变分读出，利用有源压缩，并避免在单一频率的辐射压力噪声。然后将引入滤腔以避免宽频带内的辐射压力噪声。先进的LIGO和其他第二代引力波探测器预计会受到大部分探测频带量子噪声的限制。在低频时，测试质量受辐射压力驱动；在高频时，散粒噪声限制了测量的相位精度。辐射压力和散粒噪声共同影响了未来引力波探测器的灵敏度。与LIGO科学合作组织内的其他小组合作，将提供获得压缩真空状态源的途径，这将用于直接降低辐射压力噪声。其他的拓扑结构，如速度计和双载波读出，也将被探讨。通过结合使用光捕获和冷却，机械谐振器将被置于低噪声状态，退相干率小于其振荡频率，允许谐振器被置于非经典状态，作为量子力学的测试。本研究项目将大大加强路易斯安那州立大学重力物理实验项目的校内研究活动。由于路易斯安那州立大学靠近LIGO利文斯顿天文台，以及PI在LIGO项目中的其他研究活动，因此在LIGO调试、其他现场工作和研发活动之间将有大量的人员和智力重叠。这些活动之间的整合将加强LIGO项目，降低风险，并推进引力波科学的前沿。具有小规模实验室实验和大型科学合作经验的学生和博士后将接受培训。这项工作的性质自然导致GW社区与量子光学和量子信息领域之间的合作。热噪声表征实验将广泛应用于许多受热噪声限制的系统。一项针对大三本科生的暑期研究和教育计划将被开发出来，其目标是鼓励和帮助该地区代表性不足的群体进入LIGO科学合作组织的研究生院并取得成功。该项目将包含研究和教育两个部分，并将与现有项目紧密合作，包括LIGO科学教育中心、巴吞鲁日南方大学的廷巴克图学院，以及LIGO科学合作组织的外展小组，共同开发教育项目并吸引学生。

This award supports tabletop experiments to study methods for mitigating quantum noise in gravitational-wave interferometers. An experimental setup limited by both radiation pressure and shot noise in a low noise cryogenic environment will be developed. To achieve this in a small scale prototype, micro-fabricated mechanical resonators (of order 100 nanograms) will be used as one mirror of a high finesse optical cavity inside a low vibration cryostat, cooled to below 10K. A series of experiments will then be performed to verify models of quantum noise, and to test methods for its reduction. Specifically, a homodyne detector will be used to perform a variational readout of the resonator's position, to exploit the ponderomotive squeezing, and to evade the radiation pressure noise at a single frequency. A filter cavity will then be introduced to evade the radiation pressure noise in a wide frequency band. Advanced LIGO and other second generation gravitational wave detectors are expected to be limited by quantum noise across the majority of their detection frequency band. At low frequencies, the test masses are driven by radiation pressure and at high frequencies, shot noise limits the phase precision of the measurement. Together, the radiation pressure and shot noise represent a significant limit on the sensitivities of future gravitational-wave detectors. Collaboration with other groups within the LIGO Scientific Collaboration will provide access to a source of squeezed vacuum states, which will be used to directly reduce the radiation pressure noise. Alternative topologies, such as the speedmeter and dual-carrier readout, will also be explored. By using a combination of optical trapping and cooling, the mechanical resonators will be placed into low noise states, with decoherence rates less than their oscillation frequency, allowing for the resonators to be placed in non-classical states, as a test of quantum mechanics. This research program will substantially enhance the on-campus research activities of the experimental gravitational physics program at Louisiana State University. Because of LSU's proximity to the LIGO Livingston Observatory, and the PI's other research activities within the LIGO project, there will be substantial personnel and intellectual overlap between LIGO commissioning, other on-site work, and R&D activities. Integration among these activities will strengthen the LIGO project and reduce risk, as well as advance the frontier of gravitational-wave science. Students and post-docs with experience in both small scale lab experiments and large scientific collaborations will be trained. The nature of this work naturally leads to collaboration between the GW community and the fields of quantum optics and quantum information. The thermal noise characterization experiments will have wide ranging applications to many systems limited by thermal noise. A summer research and education program aimed at undergraduate juniors will be developed, with the goal of encouraging and helping underrepresented groups in the region enter and succeed in graduate school within the LIGO Scientific Collaboration. This program will contain both a research and an education component, and will work strongly with existing programs including the LIGO Science Education Center, Southern University Baton Rouge's Timbuktu Academy, and the outreach group in the LIGO Scientific Collaboration to develop the educational program and to attract students.