Scattering loss in precision metrology due to mirror roughness

Area of Science:

• Quantum optics and metrology
• Gravitational wave detection instrumentation

Background:

• Optical losses degrade laser interferometric instrument sensitivity by reducing signal photons and introducing noise.
• In quantum-enhanced metrology, optical losses cause decoherence, breaking photon entanglement and hindering quantum noise reduction.

Purpose of the Study:

• To compare direct measurements of optical losses with numerical simulations in a gravitational-wave detector prototype.
• To develop a unified approach for estimating total optical loss in cavities for quantum-enhanced precision metrology.

Main Methods:

• Direct measurement of cavity and mirror losses in the Caltech 40 m gravitational-wave detector prototype interferometer.
• Semi-analytic intra-cavity wavefront simulations utilizing mirror surface profile maps.

Main Results:

• Validation of numerical simulation accuracy against direct loss measurements.
• Demonstration of a unified approach to quantify optical losses in interferometer cavities.

Conclusions:

• Accurate estimation of optical losses is vital for minimizing decoherence in quantum-enhanced precision metrology.
• The developed method aids in engineering systems with reduced decoherence for advanced metrology applications, including gravitational wave detectors.