Scattering Loss in Precision Metrology due to Mirror Roughness

TL;DR

This paper investigates optical scattering losses caused by mirror surface roughness in precision interferometry, comparing measurements with simulations to improve cavity loss estimates for quantum-enhanced metrology.

Contribution

It introduces a unified approach combining measurements and simulations to accurately estimate optical losses in gravitational-wave detectors.

Findings

Measured cavity and mirror losses in a prototype interferometer.

Compared measurements with semi-analytic wavefront simulations.

Proposed a method for minimizing decoherence in quantum metrology systems.

Abstract

Optical losses degrade the sensitivity of laser interferometric instruments. They reduce the number of signal photons and introduce technical noise associated with diffuse light. In quantum-enhanced metrology, they break the entanglement between correlated photons. Such decoherence is one of the primary obstacles in achieving high levels of quantum noise reduction in precision metrology. In this work, we compare direct measurements of cavity and mirror losses in the Caltech 40m gravitational-wave detector prototype interferometer with numerical estimates obtained from semi-analytic intra-cavity wavefront simulations using mirror surface profile maps. We show a unified approach to estimating the total loss in optical cavities (such as the LIGO gravitational detectors) that will lead towards the engineering of systems with minimum decoherence for quantum-enhanced precision metrology.