Herriott-Cavity-Assisted Closed-Loop Xe Isotope Comagnetometer

TL;DR

This paper introduces a Herriott-cavity-assisted Xe isotope comagnetometer that enhances stability and sensitivity for precision measurements of anomalous fields affecting proton and neutron spins.

Contribution

It presents a novel passive cavity method to improve Rb magnetometer sensitivity and demonstrates a dual comagnetometer system for independent spin coupling measurements.

Findings

Achieved an ARW of 0.06 °/h^{1/2} and bias instability of 0.2 °/h.

Implemented a Herriott cavity to enhance magnetometer stability.

Extended system allows simultaneous measurement of proton and neutron spin couplings.

Abstract

We present in this paper a Herriott-cavity-assisted closed-loop Xe isotope gas comagnetometer. In this system, $^{129}$Xe and $^{131}$Xe atoms are pumped and probed by polarized Rb atoms, and continuously driven by oscillating magnetic fields, whose frequencies are kept on resonance by phase-locked loops (PLLs). Different from other schemes, we use a Herriott cavity to improve the Rb magnetometer sensitivity instead of the parametric modulation method, and this passive method is aimed to improve the system stability while maintaining the sensitivity. This system has demonstrated an angle random walk (ARW) of 0.06 $^\circ$/h$^{1/2}$, and a bias instability of 0.2 $^\circ$/h (0.15 $\mu$Hz) with a bandwidth of 1.5 Hz. By adding a closed-loop Rb isotope comagnetometer, we can extend this system to dual simultaneously working comagnetometers sharing the same cell. This extended system has wide applications in precision measurements, where we can simultaneously and independently measure the coupling of anomalous fields with proton spin and neutron spin.