Tests of relativity using a microwave resonator

TL;DR

This study uses cryogenic sapphire oscillators and hydrogen masers to perform Michelson-Morley and Kennedy-Thorndike tests, setting new constraints on Lorentz invariance violations with improved precision over previous experiments.

Contribution

The paper presents the first use of a cryogenic sapphire oscillator combined with a hydrogen maser for Lorentz invariance tests, achieving significantly tighter constraints.

Findings

Constraints on Lorentz invariance violation parameters improved by up to 30 times.

No evidence found for Lorentz invariance violation within experimental sensitivity.

Results set new upper bounds on parameters of the Mansouri and Sexl test theory.

Abstract

The frequencies of a cryogenic sapphire oscillator and a hydrogen maser are compared to set new constraints on a possible violation of Lorentz invariance. We determine the variation of the oscillator frequency as a function of its orientation (Michelson-Morley test) and of its velocity (Kennedy-Thorndike test) with respect to a preferred frame candidate. We constrain the corresponding parameters of the Mansouri and Sexl test theory to $\delta - \beta + 1/2 = (1.5\pm 4.2) \times 10^{-9}$ and $\beta - \alpha - 1 = (-3.1\pm 6.9) \times 10^{-7}$ which is equivalent to the best previous result for the former and represents a 30 fold improvement for the latter.