Optimal Estimation of Parameters Encoded in Quantum Coherent State Quadratures

Abstract

In the context of multiparameter quantum estimation theory, we investigate the construction of linear schemes in order to infer two classical parameters that are encoded in the quadratures of two quantum coherent states. The optimality of the scheme built on two phase-conjugate coherent states is proven with the saturation of the quantum Cramér−Rao bound under some global energy constraint. In a more general setting, we consider and analyze a variety of n-mode schemes that can be used to encode n classical parameters into n quantum coherent states and then estimate all parameters optimally and simultaneously.

Keywords

• quantum estimation theory
• quantum cramér–rao bound
• quantum fisher information
• quantum optics
• quantum coherent states
• phase conjugation