Atom Interferometry tests of the isotropy of post-Newtonian gravity

TL;DR

This paper reports a highly sensitive atom interferometry experiment testing the isotropy of gravity, setting new limits on anisotropic gravity coefficients within the SME framework, thus advancing tests of fundamental physics principles.

Contribution

It introduces the highest resolution atom interferometer to date for gravity measurements and provides new experimental bounds on anisotropic gravity coefficients in the SME model.

Findings

Limits four anisotropic gravity coefficients at the ppb level.

Limits three additional coefficients at the 10ppm level.

Demonstrates the experiment compares gravity and electromagnetism isotropy.

Abstract

We present a test of the local Lorentz invariance of post-Newtonian gravity by monitoring Earth's gravity with a Mach-Zehnder atom interferometer that features a resolution of about 8*10^(-9)g/Hz^(1/2), the highest reported thus far. Expressed within the standard model extension (SME) or Nordtvedt's anisotropic universe model, the analysis limits four coefficients describing anisotropic gravity at the ppb level and three others, for the first time, at the 10ppm level. Using the SME we explicitly demonstrate how the experiment actually compares the isotropy of gravity and electromagnetism.