Testing the universality of free fall with rubidium and ytterbium in a very large baseline atom interferometer

TL;DR

This paper proposes a long baseline atom interferometer experiment using ytterbium and rubidium to test Einstein's equivalence principle with unprecedented accuracy over a 10-meter free fall, broadening the scope of EEP tests.

Contribution

It introduces a novel experimental scheme with a very long baseline atom interferometer comparing ytterbium and rubidium, achieving high precision in EEP testing and demonstrating techniques for future gravitational experiments.

Findings

Achieves an E"otv"os ratio accuracy of 7×10^{-13}

Broadens EEP test scope by comparing high atomic number elements

Demonstrates techniques for future gravimetry and gravity-gradiometry

Abstract

We propose a very long baseline atom interferometer test of Einstein's equivalence principle (EEP) with ytterbium and rubidium extending over 10m of free fall. In view of existing parametrizations of EEP violations, this choice of test masses significantly broadens the scope of atom interferometric EEP tests with respect to other performed or proposed tests by comparing two elements with high atomic numbers. In a first step, our experimental scheme will allow reaching an accuracy in the E\"otv\"os ratio of $7\times 10^{-13}$. This achievement will constrain violation scenarios beyond our present knowledge and will represent an important milestone for exploring a variety of schemes for further improvements of the tests as outlined in the paper. We will discuss the technical realisation in the new infrastructure of the Hanover Institute of Technology (HITec) and give a short overview of the requirements to reach this accuracy. The experiment will demonstrate a variety of techniques which will be employed in future tests of EEP, high accuracy gravimetry and gravity-gradiometry. It includes operation of a force sensitive atom interferometer with an alkaline earth like element in free fall, beam splitting over macroscopic distances and novel source concepts.