Thermal calcium atom interferometer comprised of three copropagating traveling laser beams

An atom interferometer was constructed using the interactions of a thermal Ca atomic beam with three copropagating traveling laser beams separated in space. A visibility of 0.25 could be obtained when the thermal atomic beam was excited by laser powers of pi/2, pi, and pi/2 pulses of the three laser beams, for atoms with the most probable velocity. The equation for the population probability of the excited atom was derived for the divergent thermal atomic beam which interacts with three laser beams of arbitrary powers. The experimental behavior was fairly well explained by the calculated results. The visibility is reduced owing to the resonance linewidth being narrower than the linewidth of the beam divergence, in addition to the Maxwell velocity distribution.