2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/217258For a mixed quantum state with density matrix $ρ$ there are infinitely many ensembles of pure quantum states, which average to $ρ$. Starting from Laplace principle of insufficient reason (not to give \emph{a priori} preference to any particular state), we derive a `natural' distribution of pure states averaging to $ρ$, which is `more spread' than all the others.11 pages, LaTeX. Talk presented at Quantum Structures - 2008 (July 6-12, 2008, Sopot, Poland)Quantum Physicstext