Quantum sources in external fields

The Schrödinger equation is homogeneous reflecting the linearity of quantum mechanics. However, we show that adding a source term provides a very convenient and flexible tool for the description of processes where an electron is generated by detachment or by ionization and subsequently propagates in the presence of an external field, which may include the detaching or the ionizing field. The source term provides the mathematical formulation of a separation of the process into two steps, detachment and subsequent propagation. We present the source formalism and illustrate it by various examples: photodetachment in the presence of a uniform electric field, the conductivity of an ideal wire, scanning tunneling microscopy, the velocity map of an electron liberated from a bound state in an atom or ion by an intense laser field and its features such as the carpet pattern, and a novel realization of the time-honored double-slit experiment by means of temporal slits afforded by an atom in a few-cycle laser pulse. All examples compare the theoretical source formulation with experimental data.