The Advanced LIGO gravitational-wave detectors are limited by optical quantum noise in most of their detection band. To overcome this limit, squeezed vacuum states have been injected into the Advanced LIGO detectors during the third observing run (O3), leading to an increase of their detection rate by about 40% to 50%. Here we present a key element of LIGO's squeezed vacuum source: the seismic isolation platform that houses core components placed in ultra-high vacuum. This paper describes the architecture of the isolation platform as well as the active control system, tuned to minimize backscattered light that otherwise deteriorates the sensitivity of the detectors. This architecture permits fewer optical Faraday isolators in the optical path of the squeezing system, minimizing optical losses to maximize the quantum noise improvement. The system reliably operated throughout LIGO's O3 with no evidence of noise from backscattered light. The innovative architecture of this platform makes it ideal for straightforward reshaping and adaptation to other gravitational-wave detector subsystems and low-noise optical instrumentation.

中文翻译：

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先进的 LIGO 挤压器平台，用于减少背向散射光和光损耗

先进的 LIGO 引力波探测器在其大部分探测波段都受到光量子噪声的限制。为了克服这一限制，在第三次观测运行 (O3) 期间，已将压缩真空状态注入 Advanced LIGO 探测器，从而将其探测率提高了约 40% 至 50%。在这里，我们展示了 LIGO 挤压式真空源的一个关键元素：隔震平台，其中包含放置在超高真空中的核心组件。本文介绍了隔离平台和主动控制系统的架构，经过调整以最大限度地减少反向散射光，否则会降低探测器的灵敏度。这种架构允许在挤压系统的光路中使用较少的光学法拉第隔离器，从而最大限度地减少光损耗，从而最大限度地提高量子噪声。该系统在整个 LIGO 的 O3 中可靠运行，没有后向散射光产生噪音的迹象。该平台的创新架构使其成为直接重塑和适应其他引力波探测器子系统和低噪声光学仪器的理想选择。