Frequency shifts in noble-gas magnetometers

TL;DR

This paper investigates frequency shifts in noble-gas magnetometers, revealing that species-dependent self-interactions cause the shifts and presenting the first observed gas phase frequency shift of $^{129}$Xe on $^3$He.

Contribution

It provides the first experimental evidence linking frequency shifts to self-interactions and rules out previous explanations, advancing understanding of noble-gas comagnetometers.

Findings

Frequency shifts are caused by species-dependent self-interactions.

First observation of $^{129}$Xe inducing a frequency shift on $^3$He.

Prior theories explaining shifts are invalidated by the results.

Abstract

Polarized nuclei are a powerful tool in nuclear spin studies and in searches for beyond-the-standard model physics. Noble-gas comagnetometer systems, which compare two nuclear species, have thus far been limited by anomalous frequency variations of unknown origin. We studied the self-interactions in a $^3$He-$^{129}$Xe system by independently addressing, controlling and measuring the influence of each component of the nuclear spin polarization. Our results directly rule out prior explanations of the shifts, and demonstrate experimentally that they can be explained by species dependent self-interactions. We also report the first gas phase frequency shift induced by $^{129}$Xe on $^3$He.