Paired carriers as a way to reduce quantum noise of multi-carrier gravitational-wave detectors

TL;DR

This paper investigates multi-carrier laser interferometers for gravitational-wave detection, demonstrating how antisymmetric carrier configurations can suppress quantum noise and potentially surpass the Standard Quantum Limit across a broad frequency range.

Contribution

It introduces a novel approach using paired carriers with specific parameter configurations to reduce quantum noise in gravitational-wave detectors.

Findings

Antisymmetric carriers can suppress quantum noise to follow the SQL at low frequencies.

Relaxing antisymmetry allows slight broadband SQL surpassing.

Combining multiple pairs enables flexible quantum noise shaping.

Abstract

We explore new regimes of laser interferometric gravitational-wave detectors with multiple optical carriers which allow to reduce the quantum noise of these detectors. In particular, we show that using two carriers with the opposite detunings, homodyne angles, and squeezing angles, but identical other parameters (the antisymmetric carriers), one can suppress the quantum noise in such a way that its spectrum follows the Standard Quantum Limit (SQL) at low frequencies. Relaxing this antisymmetry condition, it is also possible to slightly overcome the SQL in broadband. Combining several such pairs in the xylophone configuration, it is possible to shape the quantum noise spectrum flexibly.