  Controlable strong interaction of the qubit's bath with an external system
(i.e. with the bath's environment) allows for choosing the conditions under
which the decoherence of the qubit's states can be substantially decreased (in
a certain limit: completely avoided). By "substantially decreased" we mean that
the correlations which involve the bath's states prove negligible, while the
correlations between the qubit's and the environment's states can be made
ineffective during a comparatively long time interval. So, effectively, one may
choose the conditions under which, for sufficiently long time interval, the
initial state of "qubit + bath" remains unchanged, thus removing any kind of
the errors. The method has been successfully employed in the (simplified) model
of the solid-state-nuclear quantum computer (proposed by Kane).
