Multiparameter quantum estimation of noisy phase shifts

TL;DR

This paper explores a multiparameter quantum estimation approach to improve phase measurement accuracy in noisy conditions, demonstrated experimentally with two-photon states and applied to measure optical activity in fructose solutions.

Contribution

It introduces a multiparameter framework for quantum phase estimation that accounts for noise as a measurable parameter, with experimental validation using two-photon states.

Findings

Successful experimental implementation with two-photon states

Effective estimation of optical activity in fructose solutions

Scaling laws for precision with increasing photon number

Abstract

Phase estimation is the most investigated protocol in quantum metrology, but its performance is affected by the presence of noise, also in the form of imperfect state preparation. Here we discuss how to address this scenario by using a multiparameter approach, in which noise is associated to a parameter to be measured at the same time as the phase. We present an experiment using two-photon states, and apply our setup to investigating optical activity of fructose solutions. Finally, we illustrate the scaling laws of the attainable precisions with the number of photons in the probe state.