Interference fringes of the atom interferometer comprised of four copropagating traveling laser beams

Abstract
An atom interferometer comprised of four copropagating traveling laser beams has been developed using a thermal calcium atomic beam and the performance of the interference fringes was investigated experimentally. The interference fringes with a visibility of 0.2 were observed at an excitation power of 0.6 mW. The signal-to-noise ratio was about 100 at an integration time of 5 ms. The equations for the interference signal were derived from the evolution matrices of spinors and the visibility was calculated in consideration of the divergent thermal atomic beam. The experimental results were described well by the present calculation.