Atom Interferometer Based on Bragg Scattering from Standing Light Waves

We have constructed an atom interferometer by Bragg deflecting a collimated beam of metastable neon atoms from three parallel standing waves. Interference fringes have been observed using atoms Bragg scattered at up to the third order, giving a maximum of $6ħk$ transverse momentum difference between the two arms of the interferometer. In the first order case we have achieved a fringe contrast of 62% and a peak to peak signal of 1700 atoms/s. We believe this to be the highest fringe contrast that has been achieved in atom interferometers.