Characterization of atomic spin polarization lifetime of cesium vapor cells with neon buffer gas

Janet W Lou,Geoffrey A Cranch

doi:10.1063/1.5010294

Abstract

The dephasing time of spin-polarized atoms in an atomic vapor cell plays an important role in determining the stability of vapor-cell clocks as well as the sensitivity of optically-pumped magnetometers. The presence of a buffer gas can extend the lifetime of these atoms. Many vapor cell systems operate at a fixed (often elevated) temperature. For ambient temperature operation with no temperature control, it is necessary to characterize the temperature dependence as well. We present a spin-polarization lifetime study of Cesium vapor cells with different buffer gas pressures, and find good agreement with expectations based on the combined effects of wall collisions, spin exchange, and spin destruction. For our (7.5 mm diameter) vapor cells, the lifetime can be increased by two orders of magnitude by introducing Ne buffer gas up to 100 Torr. Additionally, the dependence of the lifetime on temperature is measured (25 - 47 oC) and simulated for the first time to our knowledge with reasonable agreement.

Highlights

Optically-pumped magnetometry is a promising technique for achieving sub-f T/Hz1/2 magnetic field resolutions.[1]
Cesium vapor cells coated with paraffin have been studied and have demonstrated a potential for extended lifetimes.[2,3,4]
The disadvantages of paraffin-coated cells are that they are difficult to fabricate, incompatible with high temperature (>80 oC) operation, and paraffin coatings have been implicated in reduced vapor density through absorption of the atoms over time.[9]

Summary

Introduction

Optically-pumped magnetometry is a promising technique for achieving sub-f T/Hz1/2 magnetic field resolutions.[1]. Characterization of atomic spin polarization lifetime of cesium vapor cells with neon buffer gas Using previously published characterizations of diffusion time, spin exchange cross-section, and spin destruction cross-section, a model is compiled to account for these collision types as a function of gas pressures and temperature.

Results

Conclusion