Nonconservative dipole forces in a two-atom system with one atom excited

Abstract: We compute the nonconservative electric dipole forces between two atoms, one of which is initially excited. These forces derive from the time variation of the longitudinal electromagnetic momentum. In contrast to the conservative van-der-Waals forces, the nonconservative forces posses components orthogonal to the interatomic axis. Thus, despite being several orders of magnitude smaller than van-der-Waals', they might be accessible experimentally for the case of two identical atoms. In addition, as with the van-der-Waals forces, the nonconservative forces present nonreciprocal constituents which result in a net force on the two-atom system. We offer an estimate of the spatial displacement caused by the nonconservative forces on a binary system of Hydrogen atoms.