Measurement of gravitational acceleration by cold atom multimode interference in the anharmonic potential

Abstract

We investigated the anharmonic effects on the dynamics and measurement accuracy of a multimode cold atomic interferometer driven by two Kapitza–Dirac pulses. The first Kapitza–Dirac pulse creates several spatially addressable modes from the ground state of an anharmonic trap and the external field. These modes evolve along different paths and coherently recombine under the anharmonic potential. The second Kapitza–Dirac pulse separates these mixed modes again. The anharmonic effect causes the asymmetry of the density distribution function of the cold atoms and it is observed at the measurement time. The expected sensitivity is calculated by the Fisher information and the Cramér–Rao lower bound. As the anharmonic effect is enhanced, the measurement accuracy of the current atomic interferometer is slightly reduced relative to the measurement accuracy Δg∕g≈10−9 in the case of a harmonic trap.