  Information encoded in networks of stationary, interacting spin-1/2 particles
is central for many applications ranging from quantum spintronics to quantum
information processing. Without control, however, information transfer through
such networks is generally inefficient. Currently available control methods to
maximize the transfer fidelities and speeds mainly rely on dynamic control
using time-varying fields and often assume instantaneous readout. We present an
alternative approach to achieving efficient, high-fidelity transfer of
excitations by shaping the energy landscape via the design of time-invariant
feedback control laws without recourse to dynamic control. Both instantaneous
readout and the more realistic case of finite readout windows are considered.
The technique can also be used to freeze information by designing energy
landscapes that achieve Anderson localization. Perfect state or super-optimal
transfer and localization are enabled by conditions on the eigenstructure of
the system and signature properties for the eigenvectors. Given the
eigenstructure enabled by super-optimality, it is shown that feedback
controllers that achieve perfect state transfer are, surprisingly, also the
most robust with regard to uncertainties in the system and control parameters.
