Optimal Control of Disordered Quantum Systems

We investigate several control strategies for the transport of an excitation along a spin chain. We demonstrate that high fidelity transport at the quantum speed limit can be achieved using protocols designed with differentiable programming. Building on this, show that this approach can be effectively adapted to control a disordered quantum system. We consider two settings: optimal control for a known, unwanted disorder pattern (i.e. a specific disorder realisation) and optimal control where only the disorder structure is known (i.e. optimising for high average fidelities). In the former, the disorder effects can be effectively countered for an appropriately chosen control protocol and extremely high fidelity control. However, in the latter setting the average fidelity can only be marginally improved.