Improving Sensitivity of an Amplitude-Modulated Magneto-Optical Atomic Magnetometer using Squeezed Light

TL;DR

This paper demonstrates that using a squeezed optical probe in an amplitude-modulated atomic magnetometer enhances magnetic field measurement sensitivity by 15%, confirming quantum enhancement effects in such systems.

Contribution

The study introduces a method to improve atomic magnetometer sensitivity using polarization self-rotation to generate squeezed light, extending measurement range to sub-Gauss fields.

Findings

15% sensitivity improvement with squeezed light

Extension of measurement range to sub-Gauss magnetic fields

Confirmation of quantum enhancement in modulated atomic magnetometers

Abstract

We experimentally demonstrate that a squeezed probe optical field can improve the sensitivity of the magnetic field measurements based on nonlinear magneto-optical rotation (NMOR) with an amplitude-modulated pump when compared to a coherent probe field under identical conditions. To realize an all-atomic magnetometer prototype, we utilize a nonlinear atomic interaction, known as polarization self-rotation(PSR), to produce a squeezed probe field. An independent pump field, amplitude-modulated at the Larmor frequency of the bias magnetic field, allows us to extend the range of most sensitive NMOR measurements to sub-Gauss magnetic fields. While the overall sensitivity of the magnetometer is rather low ($>250\mathrm{pT}/\sqrt{\mathrm{Hz}}$, we clearly observe a $15\%$ sensitivity improvement when the squeezed probe is used. Our observations confirm the recently reported quantum enhancement in a modulated atomic magnetometer arXiv:2108.01519 [quant-ph].