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

Abstract

We propose a very long baseline atom interferometer test of Einstein's equivalence principle (EEP) with ytterbium and rubidium extending over 10 m 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 numbfers. In the first step, our experimental scheme will allow us to reach an accuracy in the Eötvös ratio of 7 · 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 needed 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.

Correlative methods for dual-species quantum tests of the weak equivalence principle

“…Thus, high-bandwidth accelerometers are generally not required to implement the FRAC method with a single sensor. For instance, for ground-based WEP test facilities targeting a few 10 −15 [43,44,46] using interrogation times of T 1 ∼ s, we estimate that a mechanical accelerometer with a self-noise less than 10 −11 g Hz in the DC to 1 Hz frequency band will yield a phase noise contribution below the projected shot-noise limit of ∼1 mrad for each interferometer.…”

“…(4)Systematic phase shifts in d ϕ due to non-identical pulse durations j τ and Rabi frequencies j eff Ω [15] are accounted for in the estimates of j vib ϕ for each interferometer. Such systematics will be important to consider in future long-baseline differential interferometry experiments [7,[44][45][46][51][52][53][54]. (5)The relative timing between coupled interferometers can be freely chosen-they need not be overlapped.…”

“…We now compare three methods of extracting d ϕ from experimental data recorded in an environment with high vibrational noise, as in the case of onboard applications [58,69]. These studies are also applicable to future high-sensitivity differential interferometers operated in low-noise environments [44][45][46]. ϕ ≃ rad).…”

Inertial quantum sensors using light and matter

“…These devices are so precise that they are used today as references for fundamental constants (mass, gravity), and are powerful candidates to test the theory of General Relativity on surface-based [18,19,20], subterranean [21] or in Space-based laboratories [22,23]. Projects are currently underway to verify the universality of free fall (UFF) [19,24,20,23,25,26,27], to detect gravitational waves in a frequency range yet unreachable with current laser-based detectors [28,29,30], and to test dark energy [31,32]. Nowadays, many efforts are devoted to designing compact, robust and mobile sensors [33,34].…”

Focus on gravitational quantum physics

“…In that spirit, the bulk of papers by experimental groups are in-depth studies of novel ways to test Einstein's equivalence principle on quantum systems. Hartwig et al develop a proposal for testing the universality of free fall for two elements with high atomic numbers, rubidium and ytterbium, in a very large baseline atom interferometer [17]. Barrett et al describe and demonstrate two new methods for extracting the differential phase between dual-species atom interferometers for precise tests of the weak equivalence principle [18].…”