Influence of chirping the Raman lasers in an atom gravimeter: phase shifts due to the Raman light shift and to the finite speed of light

摘要

We present here an analysis of the influence of the frequency dependence ofthe Raman laser light shifts on the phase of a Raman-type atom gravimeter.Frequency chirps are applied to the Raman lasers in order to compensate gravityand ensure the resonance of the Raman pulses during the interferometer. We showthat the change in the Raman light shift when this chirp is applied only to oneof the two Raman lasers is enough to bias the gravity measurement by a fractionof $\mu$Gal ($1~\mu$Gal~=~$10^{-8}$~m/s$^2$). We also show that this effect isnot compensated when averaging over the two directions of the Raman wavevector$k$. This thus constitutes a limit to the rejection efficiency of the$k$-reversal technique. Our analysis allows us to separate this effect from theeffect of the finite speed of light, which we find in perfect agreement withexpected values. This study highlights the benefit of chirping symmetricallythe two Raman lasers.