Submitted for the DAMOP15 Meeting of The American Physical Society Quantum Tests of the Universality of Free Fall DENNIS SCHLIPPERT, HENNING ALBERS, CHRISTIAN MEINERS, LOGAN L. RICHARDSON, ETIENNEWODEY, HENDRIK HEINE, DIPANKAR NATH, CHRISTIAN SCHUBERT, WOLFGANG ERTMER, ERNST M. RASEL, Institut fuer Quantenoptik, Leibniz Universitaet Hannover — Searches for violations of the Universality of Free Fall (UFF) mark an important approach in reconciling quantum mechanics and general relativity. In this respect, matter wave interferometers resemble a novel test method that differs fundamentally from experiments employing macroscopic test masses. We report on a quantum test of the UFF at the 100 ppb level using two different chemical elements, 39K and 87Rb [1]. We show recent improvements of the experiment aiming towards a ppb test, focusing on both, the stability, and the systematic uncertainty aided by the use of a common optical dipole trap. We furthermore present future strategies for tests of the UFF aiming for accuracies of 10−13 and beyond in large scale apparatuses on ground and in space. [1] D. Schlippert et al., Phys. Rev. Lett. 112, 203002 (2014) Dennis Schlippert Institut fuer Quantenoptik, Leibniz Universitaet Hannover Date submitted: 30 Jan 2015 Electronic form version 1.4

To date, no framework combining quantum field theory and general relativity and hence unifying all four fundamental interactions, exists. Violations of the Einstein's equivalence principle (EEP), being the foundation of general relativity, may hold the key to a theory of quantum gravity. The universality of free fall (UFF), which is one of the three pillars of the EEP, has been extensively tested with classical bodies. Quantum tests of the UFF, e.g. by exploiting matter wave interferometry, allow for complementary sets of test masses, orders of magnitude larger test mass coherence lengths and investigation of spin-gravity coupling. We review our recent work towards highly sensitive matter wave tests of the UFF on ground. In this scope, the first quantum test of the UFF utilizing two different chemical elements, Rb-87 and K-39, yielding an Eötvös ratio η_ Rb,K=(0.3± 5.4)× 10^-7 has been performed. We assess systematic effects currently limiting the measurement at a level of parts in 10^8 and finally present our strategies to improve the current state-of-the-art with a test comparing the free fall of rubidium and ytterbium in a very long baseline atom interferometry setup. Here, a 10 m baseline combined with a precise control of systematic effects will enable a determination of the Eötvös ratio at a level of parts in 10^13 and beyond, thus reaching and overcoming the performance limit of the best classical tests.