Squeezing and Dual Recycling in Laser Interferometric Gravitational Wave Detectors

TL;DR

This paper analyzes how dual recycling and squeezed light can be combined in laser interferometric gravitational wave detectors to improve sensitivity by reducing photon counting noise, considering frequency-dependent effects.

Contribution

It provides a detailed calculation of the interferometer response incorporating both dual recycling and squeezing, highlighting their combined effect on noise reduction.

Findings

Both squeezing and dual recycling reduce photon counting noise.

The combined techniques enable more precise phase measurements.

Photon number variance oscillates at gravitational wave frequency.

Abstract

We calculate the response of an ideal Michelson interferometer incorporating both dual recycling and squeezed light to gravitational waves. The photon counting noise has contributions from the light which is sent in through the input ports as well as the vacuum modes at sideband frequencies generated by the gravitational waves. The minimum detectable gravity wave amplitude depends on the frequency of the wave as well as the squeezing and recycling parameters. Both squeezing and the broadband operation of dual recycling reduce the photon counting noise and hence the two techniques can be used together to make more accurate phase measurements. The variance of photon number is found to be time-dependent, oscillating at the gravity wave frequency but of much lower order than the constant part.