  Spin chains have long been considered as candidates for quantum channels to
facilitate quantum communication. We consider the transfer of a single
excitation along a spin-1/2 chain governed by Heisenberg-type interactions. We
build on the work of Balachandran and Gong [1], and show that by applying
optimal control to an external parabolic magnetic field, one can drastically
increase the propagation rate by two orders of magnitude. In particular, we
show that the theoretical maximum propagation rate can be reached, where the
propagation of the excitation takes the form of a dispersed wave. We conclude
that optimal control is not only a useful tool for experimental application,
but also for theoretical enquiry into the physical limits and dynamics of
many-body quantum systems.

Quantum Physics