A Quantum-Enhanced Prototype Gravitational-Wave Detector

TL;DR

This paper demonstrates a 44% improvement in the sensitivity of a prototype gravitational-wave detector by injecting a squeezed state of light, advancing quantum-enhanced measurement techniques for astrophysical observations.

Contribution

It presents the first significant implementation of quantum squeezing in a prototype GW detector, improving displacement sensitivity by 44%.

Findings

Achieved 44% sensitivity improvement with squeezed light.

Demonstrated feasibility of quantum squeezing in GW detection.

Paved the way for quantum enhancement in large-scale GW observatories.

Abstract

The quantum nature of the electromagnetic field imposes a fundamental limit on the sensitivity of optical precision measurements such as spectroscopy, microscopy, and interferometry. The so-called quantum limit is set by the zero-point fluctuations of the electromagnetic field, which constrain the precision with which optical signals can be measured. In the world of precision measurement, laser-interferometric gravitational wave (GW) detectors are the most sensitive position meters ever operated, capable of measuring distance changes on the order of 10^-18 m RMS over kilometer separations caused by GWs from astronomical sources. The sensitivity of currently operational and future GW detectors is limited by quantum optical noise. Here we demonstrate a 44% improvement in displacement sensitivity of a prototype GW detector with suspended quasi-free mirrors at frequencies where the sensitivity is shot-noise-limited, by injection of a squeezed state of light. This demonstration is a critical step toward implementation of squeezing-enhancement in large-scale GW detectors.