Quantum-enhanced weak absorption estimation with correlated photons

TL;DR

This paper introduces a quantum-enhanced measurement strategy using correlated photons to estimate weak absorption levels with high precision, surpassing classical shot noise limits and enabling non-damaging probing of fragile systems.

Contribution

It presents a novel quantum correlation-based measurement method for weak absorption estimation, achieving single-photon level sensitivity in noisy environments.

Findings

Capable of estimating weak absorption down to a single photon

Achieves precision comparable to 1000 photons in classical methods

Enables non-damaging probing of fragile systems

Abstract

Conventional absorption spectroscopy relies on coherent laser sources, and in turn suffers from the inherent limitation of shot noise, especially in estimating weak absorption. Here we propose a measurement strategy with correlated photons to determine the weak absorption by distinguishing the output with and without photons, dubbed as the on-off measurement. We demonstrate that absorption spectroscopy that incorporates quantum correlations is capable of estimating weak absorption down to a single-photon level, even in noisy environments, achieving a precision comparable to that obtained through 1000 photons in conventional absorption spectroscopy. Our strategy provides a new method to probe fragile systems with weak absorption, avoiding the occurrence of light-induced damage.