Twin-lattice atom interferometers using thousands of photon recoils*

Atom interferometry offers an interesting perspective for the detection of gravitational waves in the frequency band between eLISA and Advanced LIGO. A key feature to reach the targeted sensitivities for these devices is large momentum transfer. Optical lattices are ideal tools to transfer large number of photon recoils onto atoms. We demonstrate twin-lattice atom interferometers with up to 1632 photon recoils at a maximum splitting of 408 photon recoils, which is to our best knowledge the largest in an interferometer reported so far. To reach these large momentum splittings while maintaining interferometric contrast, we utilize delta-kick collimated Bose-Einstein condensates. The main cause for loss of contrast in these interferometers are distortion on the lattice light field. In our setup we can verify by simulations, that these distortions are caused by aperture effects of the Gaussian beam and show an increased contrast by a factor of 3. We study the influence of these light field distortions and show the implementation of a top-hat-shaped laser beam to surpass our current limitations.