Strong Field Ionization as an Inhomogeneous Schroedinger Equation

Abstract

Strong field ionization is difficult to treat theoretically due to the simultaneous need to treat bound state dynamics accurately and continuum dynamics efficiently. We address this problem by decomposing the time dependent Schroedinger equation (TDSE) into an inhomogeneous form, in which a precomputed bound state acts as a source term for a time dependent tunneling component. The resulting theory is equivalent to the full TDSE when exact propagation is used, and reduces or eliminates a major source of wavefunction error when propagation is approximated. The gauge invariance of the resulting theory is used to clarify an apparent gauge dependence which has long been observed in the context of strong field S-matrix theory.