2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/90256We propose a scheme to produce the pure entangled states through type II downconversion. In the scheme, the vacuum states are excluded and the a prori pure entangled states are produced and verified without destroying the state itself. This can help to carry out the many unditional experiments related to quantum entanglement.8 pages. 4 figuresQuantum Physicstext