A large sample study of spin relaxation and magnetometric sensitivity of paraffin-coated Cs vapor cells

TL;DR

This study characterizes over 250 paraffin-coated Cs vapor cells, analyzing their relaxation rates and magnetometric sensitivities, revealing high-performance cells with sensitivities near fundamental noise limits for multi-channel atomic magnetometry.

Contribution

It provides a comprehensive experimental analysis of relaxation rates and sensitivities in a large sample of Cs vapor cells, identifying key factors affecting performance.

Findings

Best cell relaxation rates: $ ext{sGamma}_{01}/2 ext{pi} ext{≈} 0.5 Hz$, $ ext{sGamma}_{02}/2 ext{pi} ext{≈} 2 Hz$

90% of cells achieve sensitivities between 9 and 30 fT/Hz^{1/2}

Magnetometers operate near the photon shot noise limit.

Abstract

We have manufactured more than 250 nominally identical paraffin-coated Cs vapor cells (30 mm diameter bulbs) for multi-channel atomic magnetometer applications. We describe our dedicated cell characterization apparatus. For each cell we have determined the intrinsic longitudinal, $\sGamma{01}$, and transverse, $\sGamma{02}$, relaxation rates. Our best cell shows $\sGamma{01}/2\pi\approx 0.5 Hz, and $\sGamma{02}/2\pi\approx 2 Hz. We find a strong correlation of both relaxation rates which we explain in terms of reservoir and spin exchange relaxation. For each cell we have determined the optimal combination of rf and laser powers which yield the highest sensitivity to magnetic field changes. Out of all produced cells, 90% are found to have magnetometric sensitivities in the range of 9 to 30 fTHz. Noise analysis shows that the magnetometers operated with such cells have a sensitivity close to the fundamental photon shot noise limit.