2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/136370We simplify some conjectures in quantum information theory; the additivity of minimal output entropy, the multiplicativity of maximal output p-norm and the superadditivity of convex closure of output entropy. We construct a unital channel for a given channel so that they share the above additivity properties; we can reduce the conjectures for all channels to those for unital channels.8 pagesQuantum Physicstext