2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/99274We consider bistochastic quantum channels generated by unitary representations of the discret group. The proof of the additivity conjecture for the quantum depolarizing channel $Φ$ based on the decreasing property of the relative entropy is given. We show that the additivity conjecture is true for the channel $Ξ=Ψ\circ Φ$, where $Ψ$ is the phase damping.11 pagesQuantum Physicstext