Quantum multiparameter metrology with generalized entangled coherent state

TL;DR

This paper introduces a generalized entangled coherent state for quantum multiparameter metrology, demonstrating improved precision in estimating multiple phase shifts in optical interferometry compared to previous states.

Contribution

It proposes a new generalized entangled coherent state and analyzes its effectiveness in multiparameter quantum metrology, showing enhanced precision over existing states.

Findings

Generalized ECS outperforms generalized NOON states in precision.

Simultaneous estimation offers advantages for multiple parameters.

Linear and nonlinear protocols show similar benefits with respect to parameter number.

Abstract

We propose a generalized form of entangled coherent states (ECS) and apply them in a multi-arm optical interferometer to estimate multiple phase shifts. We obtain the quantum Cramer-Rao bounds for both the linear and nonlinear parameterization protocols. Through the analysis, we find that, utilizing the simultaneous estimation, this generalized form of ECS gives a better precision than the generalized NOON states [Phys. Rev. Lett. \textbf{111}, 070403 (2013)]. Moreover, comparing with the independent estimation, both the linear and nonlinear protocols have the same advantage in the relation to the number of the parameters.