2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/91440Matter waves originating from a localized region in space appear commonly in physics. Examples are photo-electrons, ballistic electrons in nanotechnology devices (scanning-tunneling microscopy, quantum Hall effect), or atoms released from a coherent source (atom laser). We introduce the energy-dependent Green function as a suitable tool to calculate the arising currents. For some systems experimental data is available and in excellent agreement with the presented results.8 pages, 4 figures, to be published in the proceedings of the ICSSUR 2003, Puebla, MexicoQuantum Physicstext