Quantum Limits of Position and Polarizability Estimation in the Optical Near Field

TL;DR

This paper demonstrates that optical near fields provide more information for estimating a scatterer's position and polarizability than far fields, revealing fundamental quantum limits in near-field sensing.

Contribution

It introduces a quantum estimation framework showing near fields contain more information than far fields for scatterer characterization.

Findings

Near fields carry more information about scatterer parameters.

The paper derives the fundamental localization limit in free space.

Near-field measurements improve sensing precision.

Abstract

Optical near fields are at the heart of various applications in sensing and imaging. We investigate dipole scattering as a parameter estimation problem and show that optical near-fields carry more information about the location and the polarizability of the scatterer than the respective far fields. This increase in information originates from and occurs simultaneously with the scattering process itself. Our calculations also yield the far-field localization limit for dipoles in free space.