Quantum Enhanced Multiple Phase Estimation

TL;DR

This paper demonstrates quantum strategies that improve the simultaneous estimation of multiple phases, offering advantages over classical and individual quantum methods, with practical considerations for implementation.

Contribution

It introduces quantum probe states that enhance multi-phase estimation and analyzes their practical attainability with realistic detectors.

Findings

Quantum probes outperform classical strategies in multi-phase estimation.

The variance improvement scales as O(d) with the number of phases.

Realistic probes and detectors can approach the theoretical advantage.

Abstract

We study the simultaneous estimation of multiple phases as a discretised model for the imaging of a phase object. We identify quantum probe states that provide an enhancement compared to the best quantum scheme for the estimation of each individual phase separately, as well as improvements over classical strategies. Our strategy provides an advantage in the variance of the estimation over individual quantum estimation schemes that scales as O(d) where d is the number of phases. Finally, we study the attainability of this limit using realistic probes and photon-number-resolving detectors. This is a problem in which an intrinsic advantage is derived from the estimation of multiple parameters simultaneously.