Increasing the sensitivity of future gravitational-wave detectors with double squeezed-input

TL;DR

This paper proposes a method to enhance gravitational-wave detector sensitivity by injecting two filtered squeezed vacuums, significantly reducing quantum noise across the detection band, with practical parameter optimization for Advanced LIGO.

Contribution

It introduces a novel double squeezed-input scheme with optimized parameters, improving sensitivity over previous single squeezed vacuum methods for gravitational-wave detection.

Findings

Quantum noise reduced by a factor of 10 at high frequencies

Scheme surpasses technical noise levels at low and intermediate frequencies

Optimized parameters tailored for detecting NSNS binaries and Bursts

Abstract

We consider improving the sensitivity of future interferometric gravitational-wave detectors by simultaneously injecting two squeezed vacuums (light), filtered through a resonant Fabry-Perot cavity, into the dark port of the interferometer.The same scheme with single squeezed vacuum was first proposed and analyzed by Corbitt et al. Here we show that the extra squeezed vacuum, together with an additional homodyne detection suggested previously by one of the authors, allows reduction of quantum noise over the entire detection band. To motivate future implementations, we take into account a realistic technical noise budget for Advanced LIGO (AdvLIGO) and numerically optimize the parameters of both the filter and the interferometer for detecting gravitational-wave signals from two important astrophysics sources, namely Neutron-Star--Neutron-Star (NSNS) binaries and Bursts. Assuming the optical loss of the 30m filter cavity to be 10ppm per bounce and 10dB squeezing injection, the corresponding quantum noise with optimal parameters lowers by a factor of 10 at high frequencies and goes below the technical noise at low and intermediate frequencies.