Quantum test of the Universality of Free Fall using rubidium and potassium

Abstract

We report on an improved test of the Universality of Free Fall using a rubidium-potassium dual-species matter wave interferometer. We describe our apparatus and detail challenges and solutions relevant when operating a potassium interferometer, as well as systematic effects affecting our measurement. Our determination of the Eötvös ratio yields $\hat{I}{\cdot }_{\text{Rb,K}}=-1.9\times 10^{-7}$ with a combined standard uncertainty of $\ddot{I}{ƒ}_{\hat{I}}\cdot =3.2\times 10^{-7}$.