Quantum variational measurement in the next generation gravitational-wave detectors

TL;DR

This paper proposes a quantum variational measurement method using a short filter cavity to surpass the Standard Quantum Limit in next-generation gravitational-wave detectors, effectively reducing low-frequency radiation pressure noise.

Contribution

It introduces a simple quantum variational measurement technique with a short filter cavity to improve low-frequency sensitivity in gravitational-wave detection.

Findings

Reduces radiation pressure noise below 100 Hz to levels comparable with non-quantum noises

Demonstrates feasibility of using a short filter cavity for quantum noise reduction

Enhances low-frequency detection capabilities in advanced gravitational-wave detectors

Abstract

A relatively simple method of overcoming the Standard Quantum Limit in the next-generation Advanced LIGO gravitational wave detector is considered. It is based on the quantum variational measurement with a single short (a few tens of meters) filter cavity. Estimates show that this method allows to reduce the radiation pressure noise at low frequencies ($<100 \mathrm{Hz}$) to the level comparable with or smaller than the low-frequency noises of non-quantum origin (mirrors suspension noise, mirrors internal thermal noise, and gravity gradients fluctuations).