  We demonstrate the use of trapped ytterbium ions as quantum bits for quantum
information processing. We implement fast, efficient state preparation and
state detection of the first-order magnetic field-insensitive hyperfine levels
of 171Yb+, with a measured coherence time of 2.5 seconds. The high efficiency
and high fidelity of these operations is accomplished through the stabilization
and frequency modulation of relevant laser sources.
