Simultaneous Dual-Species Atom Interferometry

In the context of testing the Weak Equivalence Principle (WEP) with matter-wave accelerometers, some projects under development aim to compare the acceleration of two different atomic species during few seconds of free fall in order to achieve highly sensitive measurements.\footnote{S. Dimopoulos et al., Phys. Rv. Lett. 98, 111102 (2007)}$^,$\footnote{H. M\"{u}ntiga et al., Phys Rev. Lett. 110, 093602 (2013)}$^,$\footnote{R. Geiger et al., Nature Commun. 2, 474 (2011)} A simultaneous interrogation of both atomic species is crucial to fully take advantage of a differential measurement. We report the realization of an atom interferometer based on Raman transitions which simultaneously interrogates both isotopes of Rubidium.\footnote{A. Bonnin et al., Phys. Rev. A 88, 043615 (2013)} The simultaneous aspect of our experiment allows the resolution of the differential accelerometer to remain lower than 7.10$^{-9}g$ even with vibration levels up to 3.10$^{-3}g$ thanks to common-mode vibration noise rejection. These results exhibit a rejection ratio of 90 dB. An atom based test of the WEP has been carried out leading to a differential free fall measurement between both isotopes of $\Delta g/g=(1.2 \pm 3.2)\times 10^{-7}$.