Light narrowing of cesium magnetic-resonance lines in a radio-frequency atomic magnetometer

Yangying Fu,Xiaohu Liu,Jie Yuan

doi:10.1063/1.5043231

Abstract

The magnetic-resonance lines of alkali atoms are broadened considerably by the spin-exchange collisions for a radio-frequency magnetometer operating at high temperature. The resonance linewidths of cesium atoms are derived by solving the relaxation equations. When spin-exchange relaxation dominates, a light narrowing effect is predicted. For the cesium atomic radio-frequency magnetometer operates at high temperature, a remarkable narrowing of the cesium magnetic-resonance lines are observed by increasing the pump power. The Cs-Cs spin-exchange relaxation is partially suppressed by light narrowing. This study helps to expand the applications of radio-frequency magnetometers in the high-sensitivity radio-frequency magnetic-field detection.

Highlights

The existing optical magnetometers, such as scalar magnetometers, SERF (Self-Exchange Relaxation-Free) magnetometers, and NMOR (Nonlinear Magnetic-Optical Rotation) magnetometers are generally used for the detection of static or quasi-static magnetic fields, with their sensitivity reduces at high frequency
In order to enhance the optical rotation signal, the rf magnetometer typically operates at a high temperature
When the Cs-Cs spin-exchange relaxation dominates, a narrowing of the cesium magnetic-resonance linewidth is predicted as the pump power is increased

Summary

INTRODUCTION

Biomedical applications, fundamental investigations, and radio communication need the devices which can detect radio-frequency (rf ) magnetic-field with high-sensitivity. the existing optical magnetometers, such as scalar magnetometers, SERF (Self-Exchange Relaxation-Free) magnetometers, and NMOR (Nonlinear Magnetic-Optical Rotation) magnetometers are generally used for the detection of static or quasi-static magnetic fields, with their sensitivity reduces at high frequency. The recently developed tunable rf atomic magnetometers enables the high-sensitivity detection of rf signals. In order to enhance the optical rotation signal, the rf magnetometer typically operates at a high temperature. When the Cs-Cs spin-exchange relaxation dominates, a narrowing of the cesium magnetic-resonance linewidth is predicted as the pump power is increased. The coherence strength of the Zeeman transition is proportional to the population difference ∆ρ between the two coupled sublevels, and ∆ρ = PQm. For the F = 4, m = 7/2 ground-state transition of cesium atoms pumped by a left circularly polarized light, the line broadening ∆v1 due to spin-destruction relaxation, optical pumping, and spin-exchange relaxation is. For the optical-pumping cell with high-pressure buffer gas, the resonance linewidth and the reduction factor are calculated and profiled in Figure 1 for the case of 133Cs with RSE = 2000s−1 and RSD = 20s−1 Under this condition, the spinexchange relaxation is the dominant relaxation mechanism of cesium atoms. The most significant light narrowing effect is observed at T=85◦C

EXPERIMENTAL SETUP

Findings

RESULT