Atomic Interferometer with Amplitude Gratings of Light and Its Applications to Atom Based Tests of the Equivalence Principle

Abstract

We have developed a matter wave interferometer based on the diffraction of atoms from effective absorption gratings of light. In a setup with cold rubidium atoms in an atomic fountain the interferometer has been used to carry out tests of the equivalence principle on an atomic basis. The gravitational acceleration of the two isotopes $^{85}\mathrm{R}\mathrm{b}$ and $^{87}\mathrm{R}\mathrm{b}$ was compared, yielding a difference $\ensuremath{\Delta}\mathbf{g}/\mathbf{g}=(1.2\ifmmode\pm\else\textpm\fi{}1.7)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$. We also perform a differential free fall measurement of atoms in two different hyperfine states, and obtained a result of $\ensuremath{\Delta}\mathbf{g}/\mathbf{g}=(0.4\ifmmode\pm\else\textpm\fi{}1.2)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$.