2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/172295We provide a relation which describes how the entanglement of two d-level systems evolves as either system undergoes an arbitrary physical process. The dynamics of the entanglement turns out to be of a simple form, and is fully captured by a single quantity.4 pages, 1 figure; new title and introduction, added references, some makeup; published versionQuantum Physicstext