2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/89696An alternative presentation of the Oxford purification protocol is obtained by using dynamical variables. I suggest to introduce the degree of separability as a purification parameter, where the purified state has a smaller degree of separability than the initial one. An improved version of the Oxford protocol is described, in which local unitary transformations optimize each step.RevTeX 4, 3 figuresQuantum Physicstext