2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/80748We analyze Haake et al. method for coarse graining quantum maps on the sphere from the point of view of realizable physical quantum operations achieved with completely positive superoperators. We conclude that sharp truncations a la Haake do not fall into this class.4 pages, 2 figuresChaotic Dynamicstext