# FisMat2017 - Submission - View

**Abstract's title**: Gravitational measurements with simultaneous atom interferometers

**Affiliation**: Università di Firenze, INFN

**Affiliation Address**: Dipartimento di Fisica e Astronomia, Università di Firenze - INFN Sezione di Firenze, Via Sansone 1, 50019 Sesto Fiorentino, Italy

**Country**: Italy

Atom interferometry [1] is a fast developing field which provides high-performance quantum sensors. Several applications are possible for these devices ranging from tests of fundamental physics (e.g. Einstein Equivalence Principle tests), metrology (e.g. measurement of the Newtonian gravitational constant G [2]), precise determination of accelerations and rotations, inertial navigation, geodesy, geophysics and engineering prospecting.

Our experimental apparatus is a vertical gravity gradiometer [3]. Rubidium cold-atom clouds are launched at different heights inside the interferometric region to probe the vertical acceleration profile due to gravity. With two or three vertically separated simultaneous interferometers, we can measure the gravity gradient and curvature [4] over different baselines.

The set up has recently performed a quantum test of the Weak Equivalence Principle comparing the free fall acceleration of atoms in two distinct hyperfine states and in their coherent superposition [5]. The quantum aspects of the WEP, remained untested so far, are made accessible by the superposition state which has no classical counterpart.

Another recent result of the setup is the experimental demonstration of a method to compensate the effects of gravity gradients in vertical atom interferometers [6]. This technique efficiently cancels the phase shift introduced by gravity gradients, which depends on the cloud initial position and velocity. The method has also been used to measure gravity gradients and curvature.

[1] *Atom Interferometry, Proceedings of the International School of Physics Enrico Fermi, Course CLXXXVIII*, edited by G. M. Tino and M. A. Kasevich (Società Italiana di Fisica and IOS Press, Amsterdam) (2014).

[2] G. Rosi, F. Sorrentino, L. Cacciapuoti, M. Prevedelli and G. M. Tino, *“Precision*

*measurement of the Newtonian gravitational constant using cold atoms”*, Nature **510**, 518–521 (2014).

[3] F. Sorrentino, Q. Bodart, L. Cacciapuoti, Y.-H. Lien, M. Prevedelli, G. Rosi, L. Salvi, and G. M. Tino*,* “*Sensitivity limits of a Raman atom interferometer as a gravity gradiometer”,* Phys. Rev. A **89**, 023607 (2014).

[4] G. Rosi, L. Cacciapuoti, F. Sorrentino, M. Menchetti, M. Prevedelli and G. M. Tino, *“**Measurement of the Gravity-Field Curvature by Atom Interferometry**”,* Phys. Rev. Lett. **114**, 013001 (2015).

[5] G. Rosi, G. D’Amico, L. Cacciapuoti, F. Sorrentino, M. Prevedelli, M. Zych, Č. Brukner and G. M. Tino, *“**Quantum test of the equivalence principle for atoms in superposition of internal energy eigenstates**”, *Nature Communications **8**, 15529, DOI 10.1038/NCOMMS15529 (2017).

[6] G. D'Amico, G. Rosi, S. Zhan, L. Cacciapuoti, M. Fattori and G. M. Tino, *“Cancelling gravity gradients in atom interferometry”*, submitted (2017).