Different sensitivities of two optical magnetometers realized in the same experimental arrangement

TL;DR

This study compares the sensitivities of optical magnetometers detecting static and oscillating magnetic fields within the same setup, revealing that the AC magnetometer is about ten times more sensitive under optimal conditions and can have its bandwidth significantly increased.

Contribution

It provides a direct comparison of DC and AC optical magnetometers in a unified setup, highlighting their different sensitivities and bandwidth behaviors, and demonstrates methods to enhance AC magnetometer performance.

Findings

AC magnetometer is about ten times more sensitive than DC magnetometer.

Bandwidth of the AC magnetometer can be increased without sensitivity loss.

Tuning the resonance frequency improves ultra-sensitive AC field measurements.

Abstract

In this article, operation of optical magnetometers detecting static (DC) and oscillating (AC) magnetic fields is studied and comparison of the devices is performed. To facilitate the comparison, the analysis is carried out in the same experimental setup, exploiting nonlinear magneto-optical rotation. In such a system, a control over static-field magnitude or oscillating-field frequency provides detection of strength of the DC or AC fields. Polarization rotation is investigated for various light intensities and AC-field amplitudes, which allows to determine optimum sensitivity to both fields. With the results, we demonstrate that under optimal conditions the AC magnetometer is about ten times more sensitive than its DC counterpart, which originates from different response of the atoms to the fields. Bandwidth of the magnetometers is also analyzed, revealing its different dependence on the light power. Particularly, we demonstrate that bandwidth of the AC magnetometer can be significantly increased without strong deterioration of the magnetometer sensitivity. This behavior, combined with the ability to tune the resonance frequency of the AC magnetometer, provide means for ultra-sensitive measurements of the AC field in a broad but spectrally-limited range, where detrimental role of static-field instability is significantly reduced.