Symmetry breaking and coherent control: the importance of the envelope

I shall review the progress of the field of ``coherent control,'' according to which control of dynamical processes is achieved by using lasers to induce (destructive or constructive) interferences between different quantum pathways leading to the same final outcome. I shall then discuss symmetry breaking stimulated by external laser fields and the role played by the relative and the ``envelope'' phase. Applications to chiral purification and the control of photo-current directionality in semiconductors will be given.