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Most of the quantum mechanical systems are open in nature - they
often interact with their surroundings quite fast, leading to de-coherence.
This issue of de-coherence is a major obstacle in physical realizations of
different quantum information processing schemes. It not only destroys
quantum coherence in individual subsystems, but as a result of that, it also
(in general), destroys entanglement among the subsystems. Different
mechanisms have been developed -- mostly specific to systems concerned --
to control this de-coherence effect, most of which aim at weakening the
system--environment interaction in a controlled manner. In the present work,
we instead, aim at inserting an ancillary system so that the environment acts
jointly on the system and the ancilla. Considering Markovian type
environmental effect, we find that one can suppress both de-coherence as
well as decay of entanglement by this method. Moreover, we find that larger
the size of the ancilla, better is the suppression mechanism. |