  We propose and analyze a new approach to the coherent control and
manipulation of quantum degrees of freedom in disordered, interacting systems
in the many-body localized phase. Our approach leverages a number of unique
features of many-body localization: a lack of thermalization, a locally gapped
spectrum, and slow dephasing. Using the technique of quantum phase estimation,
we demonstrate a protocol that enables the local preparation of a many-body
system into an effective eigenstate. This leads to the ability to encode
information and control interactions without full microscopic knowledge of the
underlying Hamiltonian. Finally, we analyze the effects of weak coupling to an
external bath and provide an estimate for the fidelity of our protocol.
