Phase noise due to vibrations in Mach-Zehnder atom interferometers

– Atom interferometers are very sensitive to accelerations and rotations. This property, which has some very interesting applications, induces a deleterious phase noise due to the seismic noise of the laboratory and this phase noise is sufficiently large to reduce the fringe visibility in many experiments. We develop a model calculation of this phase noise in the case of Mach-Zehnder atom interferometers and we apply this model to our thermal lithium interferometer. We are able to explain the observed phase noise which has been detected through the rapid dependence of the fringe visibility with the diffraction order. We think that the dynamical model developed in the present paper should be very useful to reduce the vibration induced phase noise in atom interferometers, making many new experiments feasible. Introduction. – Atom interferometers are very sensitive to inertial effects [1, 2] and this property was used to build accelerometers [3–10] and gyrometers [11–15]. Because of this large sensitivity, a high mechanical stability of the experiment is required and several experiments [6, 7, 17, 18] used an active control of the interferometer vibrations. In the present letter, we study the phase noise induced by mechanical vibrations in threegratings Mach-Zehnder thermal atom interferometers and we show that the rapid decrease of the fringe visibility with the diffraction order is largely due to this phase noise. Vibrations displace and bend the rail which holds the three diffraction gratings and we have developed a model based on elasticity theory to describe this dynamics. We are thus able to understand the contributions of various frequencies and to make a detailed evaluation of this phase noise in the case of our setup: the result is in good agreement with the phase noise value deduced from fringe visibility measurements. We have built a very stiff rail for our atom interferometer and this arrangement has revealed very efficient: the remaining phase noise is dominated by rotations of the rail, which should be reduced by a better rail suspension. (∗) E-mail:[email protected]