Real-time stabilization of the alkali-metal transverse axis orientation in nuclear spin comagnetometer by biaxial differential detection

Guanqun Lei,Xinghua Zhao,Wenfeng Wu,Zhanchao Liu,Zhen Chai,Heng Yuan

doi:10.1063/5.0062025

Abstract

Axis orientation stability has a great effect on the long-term drift performance of nuclear spin comagnetometers that utilize alkali atoms to detect the magnetic moment of nuclear spin ensembles. Previous studies have analyzed the sensitivity influence of the misalignment angle and demonstrated a post-processing calibration method in the transverse polarized comagnetometer, but there is no study on the traditional longitudinally polarized setup. We propose an innovative biaxial differential detection method to monitor the misalignment angle in the longitudinally polarized comagnetometer and then eliminate it on-line. By monitoring the amplitude difference of a reference magnetic field’s projections in a rotated measurement frame, an error signal with good linearity is obtained. Experiments showed that any misalignment angle within (−π/4, π/4) can be successfully compensated to near 0 within about 1.5 s, which is fast enough compared to the drift rate of a practical device. The new detection method is robust and insensitive to many factors, such as direct component drift and scale factor inequality, so the method can be widely used in similar devices that acquire high accurate alignment of the axis orientation, such as the spin exchange relaxation-free magnetometer.

Highlights

Nuclear spin comagnetometers utilize the nucleus Larmor precession frequency and vector atomic magnetometer to sense the magnetic field1 and inertial rotation.2–4 Benefited from the constancy of the gyromagnetic ratio and the frequency detection setup, they usually have characteristics of high precision, extremely stable scale factor,4,5 and small size.6,7 These features make them suitable for exploring new physics.8–10 Compared to other devices that have similar sensitivity, such as the superconducting quantum interference device (SQUID) magnetometer and spin exchange relaxation-free (SERF) magnetometer,11,12 the nuclear spin comagnetometer has its own advantages, such as compact size, relatively low price, and simple structure
The pump beam and probe beam are emitted by two distributed Bragg reflector (DBR) lasers
We analyzed the influence of the measurement axis misalignment angle of the alkali-metal magnetometer in a nuclear spin comagnetometer

Summary

Introduction

Nuclear spin comagnetometers utilize the nucleus Larmor precession frequency and vector atomic magnetometer to sense the magnetic field and inertial rotation. Benefited from the constancy of the gyromagnetic ratio and the frequency detection setup, they usually have characteristics of high precision, extremely stable scale factor, and small size. These features make them suitable for exploring new physics. Compared to other devices that have similar sensitivity, such as the superconducting quantum interference device (SQUID) magnetometer and spin exchange relaxation-free (SERF) magnetometer, the nuclear spin comagnetometer has its own advantages, such as compact size, relatively low price, and simple structure. Benefited from the constancy of the gyromagnetic ratio and the frequency detection setup, they usually have characteristics of high precision, extremely stable scale factor, and small size.6,7 These features make them suitable for exploring new physics.. Compared to other devices that have similar sensitivity, such as the superconducting quantum interference device (SQUID) magnetometer and spin exchange relaxation-free (SERF) magnetometer, the nuclear spin comagnetometer has its own advantages, such as compact size, relatively low price, and simple structure. These features are important in portable devices.. In the typical setup of a longitudinally polarized nuclear spin comagnetometer, there is a built-in alkali vector atomic magnetometer (VAM) probing the magnetic moments of the nucleus.

Methods

Results

Conclusion