  We present experimental measurements on a model quantum system that
demonstrate our ability to dramatically suppress qubit error rates by the
application of optimized dynamical decoupling pulse sequences in a variety of
experimentally relevant noise environments. We provide the first demonstration
of an analytically derived pulse sequence developed by Uhrig, and find novel
sequences through active, real-time experimental feedback. These new sequences
are specially tailored to maximize error suppression without the need for a
priori knowledge of the ambient noise environment. We compare these sequences
against the Uhrig sequence, and the well established CPMG-style spin echo,
demonstrating that our locally optimized pulse sequences outperform all others
under test. Numerical simulations show that our locally optimized pulse
sequences are capable of suppressing errors by orders of magnitude over other
existing sequences. Our work includes the extension of a treatment to predict
qubit decoherence under realistic conditions, including the use of
finite-duration, square $\pi$ pulses, yielding strong agreement between
experimental data and theory for arbitrary pulse sequences. These results
demonstrate the robustness of qubit memory error suppression through dynamical
decoupling techniques across a variety of qubit technologies.
