Decoherence suppression of open quantum systems through a strong coupling to non-Markovian reservoirs

In this paper, we provide a mechanism of decoherence suppression for open quantum systems in general and that for a "Schrödinger cat-like" state in particular, through strong couplings to non-Markovian reservoirs. Different from the usual strategies in the literature of suppressing decoherence by decoupling the system from the environment, here the decoherence suppression employs a strong back-reaction from non-Markovian reservoirs. The mechanism relies on the existence of the singularities (bound states) of the nonequilibrium retarded Green function, which completely determines the dissipation and decoherence dynamics of open systems. As an application, we examine the decoherence dynamics of a photonic crystal nanocavity that is coupled to a waveguide. The strong non-Markovian suppression of decoherence for the "optical cat" state is attained.