We propose a new technique to control quantum states by exploiting the decoherence due to the coupling with environment. With this technique we can get any target state, in a stable way and in an exponentially small time, as a stationary state of a semigroup (master equation) canonically derived from a microscopic Hamiltonian model. The stationary state of the system depends (i) on the interaction with the environment; (ii) on the initial state of the environment and it "inherits" some

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... s of it in a sense that will be explained in sec. 5 of the present paper. Moreover this is true not only for by thermal or vacuum environments but also for more general non-equilibrium environments. We prove that, by appropriately choosing this control parametes (interaction system-environment, initial environment state) one can drive the system to an arbitrary preassigned quantum state.