Abstract

In this paper we present a new calculation of the force on a stationary three-level atom in a bichromatic standing-wave light field (see Fig. 1). Contrary to other theoretical treatments,¹ which ignore optical pumping into the trapped state, we find that a stationary atom experiences no force when there is no difference frequency detuning (i.e., when Δ = 0). However, when there is a nonzero differential detuning (Δ ≠ 0) there can be force components that vary in both the wavelength of the optical fields and their beat wavelength. This stimulated force can be much larger than the maximum spontaneous force associated with this system. To obtain a simple physical interpretation of this force, the problem is treated in a basis that is formed from symmetric |+〉 and antisymmetric |−〉 linear combinations of the atomic ground states² (see Fig. 1).

© 1991 Optical Society of America