  Many schemes for implementing quantum information processing require that the
atomic states used have a non-zero magnetic moment, however such magnetically
sensitive states of an atom are vulnerable to decoherence due to fluctuating
magnetic fields. Dressing an atom with an external field is a powerful method
of reducing such decoherence [N. Timoney et al., Nature 476, 185], even if the
states being dressed are strongly coupled to the environment. We introduce an
experimentally simpler method of manipulating such a dressed-state qubit, which
allows the implementation of general rotations of the qubit, and demonstrate
this method using a trapped ytterbium ion.
