Modern Michelson-Morley experiment using cryogenic optical resonators.

TLDR: A new test of Lorentz invariance is performed by comparing the resonance frequencies of two orthogonal cryogenic optical resonators subject to Earth's rotation over approximately 1 yr, improving the best previous result by about 2 orders of magnitude.

Abstract: We report on a new test of Lorentz invariance performed by comparing the resonance frequencies of two orthogonal cryogenic optical resonators subject to Earth's rotation over $\ensuremath{\sim}1\text{ }\mathrm{y}\mathrm{r}$. For a possible anisotropy of the speed of light $c$, we obtain ${\ensuremath{\Delta}}_{\ensuremath{\theta}}c/{c}_{0}=(2.6\ifmmode\pm\else\textpm\fi{}1.7)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}15}$. Within the Robertson-Mansouri-Sexl (RMS) test theory, this implies an isotropy violation parameter $\ensuremath{\beta}\ensuremath{-}\ensuremath{\delta}\ensuremath{-}\frac{1}{2}=(\ensuremath{-}2.2\ifmmode\pm\else\textpm\fi{}1.5)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$, about 3 times lower than the best previous result. Within the general extension of the standard model of particle physics, we extract limits on seven parameters at accuracies down to ${10}^{\ensuremath{-}15}$, improving the best previous result by about 2 orders of magnitude.