  The need for strategies able to accurately manipulate quantum dynamics is
ubiquitous in quantum control and quantum information processing. We
investigate two scenarios where randomized dynamical decoupling techniques
become more advantageous with respect to standard deterministic methods in
switching off unwanted dynamical evolution in a closed quantum system: when
dealing with decoupling cycles which involve a large number of control actions
and/or when seeking long-time quantum information storage. Highly effective
hybrid decoupling schemes, which combine deterministic and stochastic features
are discussed, as well as the benefits of sequentially implementing a
concatenated method, applied at short times, followed by a hybrid protocol,
employed at longer times. A quantum register consisting of a chain of spin-1/2
particles interacting via the Heisenberg interaction is used as a model for the
analysis throughout.
