Gradient optical force on atoms: beyond dipole approximation

Abstract

Within the framework of the dressed states formalism, the gradient optical force when one takes account of the quadruple interaction between a neutral atom and laser radiation in resonance with it is found. This effect is essential for atomic transitions forbidden in the dipole approximation. The magnitude of the quadruple gradient force may approach that of the dipole force in the case of optical fields with a curvature much greater than the optical wavelength, for example, in the vicinity of nanometer-size structures.