2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/57740We give a simple direct proof of the Jamiolkowski criterion to check whether a linear map between matrix algebras is completely positive or not. This proof is more accesible for physicists than others found in the literature and provides a systematic method to give any set of Kraus matrices of its Kraus decomposition.12 pages (double space), no figures. Some points further clarifiedMathematical PhysicsQuantum Physicstext