  In this paper we demonstrate that the inevitable action of the environment
can be substantially weakened when considering appropriate nonstationary
quantum systems. Beyond protecting quantum states against decoherence, an
oscillating frequency can be engineered to make the system-reservoir coupling
almost negligible. Therefore, differently from previously-reported protecting
schemes, our technique does not require a previous knowledge of the state to be
protected. We show, in the domain of cavity quantum electrodynamics, how to
engineer such a nonstationary cavity mode through its dispersive interaction
with a driven two-level atom.
