Audio-band frequency-dependent squeezing

TL;DR

This paper demonstrates a scalable method to produce frequency-dependent squeezing at audio frequencies, which can enhance gravitational-wave detectors' sensitivity by overcoming quantum noise limitations.

Contribution

It introduces a high-finesse optical resonator to achieve frequency-dependent squeezing at 1.2kHz, addressing a key challenge for future gravitational-wave observatories.

Findings

Achieved frequency-dependent squeezing at 1.2kHz using a 2-m optical resonator.

Demonstrated scalability of the technology for gravitational-wave detector applications.

Improved quantum noise reduction in the audio frequency band.

Abstract

Quantum vacuum fluctuations impose strict limits on precision displacement measurements, those of interferometric gravitational-wave detectors among them. Introducing squeezed states into an interferometer's readout port can improve the sensitivity of the instrument, leading to richer astrophysical observations. However, optomechanical interactions dictate that the vacuum's squeezed quadrature must rotate by 90 degrees around 50Hz. Here we use a 2-m-long, high-finesse optical resonator to produce frequency-dependent rotation around 1.2kHz. This demonstration of audio-band frequency-dependent squeezing uses technology and methods that are scalable to the required rotation frequency, heralding application of the technique in future gravitational-wave detectors.