  The problem of automatically protecting a quantum system against noise in a
closed circuit is analyzed. A general scheme is developed built from two steps.
At first, a distillation step is induced in which undesired components are
removed to another degree of freedom of the system. Later a recovering step is
employed which the system gains back its initial density. An Optimal-Control
method is used to generate the distilling operator. The scheme is demonstrated
by a simulation of a two level byte influenced by white noise. Undesired
deviations from the target were shown to be reduced by at least two orders of
magnitude on average. The relations between the quantum version of the
classical Watt's Governor and the field of quantum information are also
discussed.
