2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/156506The coherent control of small quantum system is considered. For a two-level system coupled to an arbitrary bath we consider a pulse of finite duration. We derive the leading and the next-leading order corrections to the evolution operator due to the non-commutation of the pulse and the bath Hamiltonian. The conditions are computed that make the leading corrections vanish. The pulse shapes optimized in this way are given for $π$ and $\fracπ{2}$ pulses.9 pages, 6 figures; published versionQuantum PhysicsMesoscale and Nanoscale PhysicsStrongly Correlated Electronstext