  We present a general control-theoretic framework for constructing and
analyzing random decoupling schemes, applicable to quantum dynamical control of
arbitrary finite-dimensional composite systems. The basic idea is to design the
control propagator according to a random rather than deterministic path on a
group. We characterize the performance of random decoupling protocols, and
identify control scenarios where they can significantly weaken time scale
requirements as compared to cyclic counterparts. Implications for reliable
quantum computation are discussed.
