  We propose a method for Hamiltonian engineering in quantum information
processing architectures that requires no local control, but only relies on
collective qubit rotations and field gradients. The technique achieves a
spatial modulation of the coupling strengths via a dynamical construction of a
weighting function combined with a Bragg grating. As an example, we demonstrate
how to generate the ideal Hamiltonian for perfect quantum information transport
between two separated nodes of a large spin network. We engineer a spin chain
with optimal couplings from a large spin network, such as naturally occurring
in crystals, while decoupling all unwanted interactions. For realistic
experimental parameters, our method can be used to drive perfect quantum
information transport at room-temperature. The Hamiltonian engineering method
can be made more robust under coherence and coupling disorder by a novel
apodization scheme. Thus the method is quite general and can be used engineer
the Hamiltonian of many complex spin lattices with different topologies and
interactions.
