Physical Resources for Quantum-enhanced Phase Estimation

TL;DR

This paper investigates how quantum entanglement influences optical phase estimation, revealing that particle entanglement is essential for quantum enhancement, while mode entanglement is not, through analysis of quantum Fisher information and optical coherence.

Contribution

It provides a formalism connecting quantum Fisher information with optical coherence functions, clarifying the roles of particle and mode entanglement in quantum metrology.

Findings

Particle entanglement is necessary for quantum-enhanced phase estimation.

Mode entanglement is not required for quantum enhancement.

Quantum Fisher information relates to optical coherence functions.

Abstract

We study the role of quantum entanglement (particle entanglement and mode entanglement) in optical phase estimation by employing the first and second quantization formalisms of quantum mechanics. The quantum Fisher information (QFI) is expressed as a function of the first and second order optical coherence functions. The resulting form of the QFI elucidates the deriving metrological resources for quantum phase estimation: field intensity and photon detection correlations. In addition, our analysis confirms that mode entanglement is not required for quantum-enhanced interferometry, whereas particle entanglement is a necessary requirement.