Quantum Test of the Universality of Free Fall

TL;DR

This study uses quantum matter-wave interferometry with rubidium and potassium atoms to test the universality of free fall, achieving high-precision measurements of gravitational effects on different atomic species.

Contribution

It introduces a simultaneous quantum test of free fall using two different atomic species, demonstrating a novel approach to testing fundamental physics principles.

Findings

Eötvös ratio measured as (0.3 ± 5.4)×10⁻⁷

First simultaneous quantum test with rubidium and potassium

Strategies outlined for future precision improvements

Abstract

We simultaneously measure the gravitationally-induced phase shift in two Raman-type matter-wave interferometers operated with laser-cooled ensembles of $^{87}$Rb and $^{39}$K atoms. Our measurement yields an E\"otv\"os ratio of $\eta_{\text{Rb,K}}=(0.3\pm 5.4)\times 10^{-7}$. We briefly estimate possible bias effects and present strategies for future improvements.