  A generalization of the results of Rasetti and Zanardi concerning avoiding
errors in quantum computers by using states preserved by evolution is
presented. The concept of the dynamical symmetry is generalized from the level
of classical Lie algebras and groups, to the level of a dynamical symmetry
based on quantum Lie algebras and quantum groups (in the sense of Woronowicz).
An intrinsic dependence of the concept of dynamical symmetry on the
differential calculus (which holds also in the classical case) is stressed. A
natural connection between quantum states invariant under a quantum group
action, and quantum states preserved by the dynamical evolution is discussed.
