Magnetic Field Estimation at and beyond 1/N Scaling via an Effective Nonlinearity

TL;DR

This paper demonstrates that a double-pass atomic magnetometer can surpass traditional 1/N sensitivity scaling, potentially achieving near-ideal sensitivity without entanglement, based on quantum Fisher information simulations.

Contribution

It introduces a double-pass measurement scheme that improves magnetic field sensitivity scaling beyond 1/N without relying on entanglement.

Findings

Double-pass scheme surpasses 1/N scaling in sensitivity.

Achieves near-ideal sensitivity without entanglement.

Supported by quantum Fisher information simulations.

Abstract

We provide evidence, based on direct simulation of the quantum Fisher information, that 1/N scaling of the sensitivity with the number of atoms N in an atomic magnetometer can be surpassed by double-passing a far-detuned laser through the atomic system during Larmor precession. Furthermore, we predict that for N>>1, the proposed double-pass atomic magnetometer can essentially achieve 1/N scaling without requiring any appreciable amount of entanglement.