State independence in atom interferometry and insensitivity to acceleration and rotation

We demonstrate that for atom interferometers with lasers serving as beam splitters state independence (including freedom from Doppler effects) of the phase shift is obtained if the paths of the two interfering beams are closed and have obtained the same momentum transfer. This is also the case when the center-of-mass motion of the atoms is subject to a constant force field (acceleration). Among these interferometers the one with the simplest geometry is deduced for which the phase shift does not depend on acceleration. Its remaining sensitivity to rotation is discussed. Finally the geometry of a state-independent interferometer that is practically insensitive to both acceleration and rotation is worked out. As an application its relevance for the detection of the influence of space-time curvature on the atomic motion is studied.