A new test of local Lorentz invariance using $^{21}$Ne-Rb-K comagnetometer

TL;DR

This paper introduces a novel $^{21}$Ne-Rb-K comagnetometer to test local Lorentz invariance, achieving unprecedented sensitivity and significantly tightening constraints on Lorentz-violating coefficients.

Contribution

The study develops a new comagnetometer using $^{21}$Ne atoms and demonstrates improved limits on Lorentz invariance violation coefficients by 2 to 4 orders of magnitude.

Findings

Constrained 4 of 5 Lorentz-violating coefficients at $10^{-29}$ level.

Improved previous limits by 2 to 4 orders of magnitude.

Placed the most stringent bounds on deviations from local Lorentz invariance.

Abstract

We develop a new comagnetometer using $^{21}$Ne atoms with nuclear spin $I=3/2$ and Rb atoms polarized by spin-exchange with K atoms to search for tensor interactions that violate local Lorentz invariance. We frequently reverse orientation of the experiment and search for signals at the first and second harmonics of the sidereal frequency. We constrain 4 of the 5 spatial Lorentz-violating coefficients $c^n_{jk}$ that parameterize anisotropy of the maximum attainable velocity of a neutron at a level of $10^{-29}$, improving previous limits by 2 to 4 orders of magnitude and placing the most stringent constrain on deviations from local Lorentz invariance.