Quantum Enhanced Precision Estimation of Transmission with Bright Squeezed Light

TL;DR

This paper demonstrates quantum-enhanced measurement of transmission using bright squeezed light, achieving precision and sensitivity beyond the quantum noise limit at significantly higher power levels than previous methods.

Contribution

It introduces a method for simultaneous enhancement of measurement precision and sensitivity beyond the QNL with bright squeezed light at high power levels.

Findings

Achieved sub-QNL precision with 0.2 mW probe power

Enhanced measurement sensitivity beyond the quantum noise limit

Operated at power levels 8 orders of magnitude higher than previous work

Abstract

Squeezed light enables measurements with sensitivity beyond the quantum noise limit (QNL) for optical techniques such as spectroscopy, gravitational wave detection, magnetometry and imaging. Precision of a measurement -- as quantified by the variance of repeated estimates -- has also been enhanced beyond the QNL using squeezed light. However, sub-QNL sensitivity is not sufficient to achieve sub-QNL precision. Furthermore, demonstrations of sub-QNL precision in estimating transmission have been limited to picowatts of probe power. Here we demonstrate simultaneous enhancement of precision and sensitivity to beyond the QNL for estimating modulated transmission with a squeezed amplitude probe of 0.2 mW average (25 W peak) power, which is 8 orders of magnitude above the power limitations of previous sub-QNL precision measurements of transmission. Our approach enables measurements that compete with the optical powers of current classical techniques, but have both improved precision and sensitivity beyond the classical limit.