Characterization of noise sources in a microfabricated single-beam zero-field optically-pumped magnetometer

Area of Science:

• Atomic physics
• Magnetometry
• Quantum sensing

Background:

• Optically-pumped magnetometers (OPMs) offer high sensitivity for magnetic field measurements.
• Understanding noise sources is critical for optimizing OPM performance.
• The spin-exchange relaxation-free (SERF) regime enables ultra-low noise operation.

Purpose of the Study:

• To experimentally characterize noise sources in a miniature single-beam absorption-based OPM.
• To identify the dominant noise contributions across different frequency ranges.
• To establish upper limits for noise sources in SERF magnetometers.

Main Methods:

• Experimental noise evaluation of an OPM operating in the SERF regime.
• Analysis of noise contributions from laser intensity, frequency, polarization, cell temperature, and magnetic field coils.
• Comparison of identified noise sources with the magnetometer's overall noise spectrum.

Main Results:

• The OPM achieved a noise floor of 7 fT/√Hz.
• Low-frequency noise (DC-30 Hz) arises from sources coupling to atoms as a magnetic field.
• High-frequency noise (>30 Hz) is primarily attributed to laser intensity noise.

Conclusions:

• Experimental noise characterization provides critical insights into OPM performance limitations.
• Identified noise sources align with the magnetometer's noise spectrum above 5 Hz.
• This study establishes benchmarks for noise reduction in miniature SERF magnetometers.