Interfacing with Hamiltonian dynamics

Simple constructions and protocols are demonstrated to allow the implementation of universal quantum computation on an arbitrarily large quantum system by controlling a fixed number of spins within a noiseless setting. Pulse sequences are derived for deterministic gate operation and system cooling, which only require pulse strengths that are comparable to the intrinsic Hamiltonian of the system. The analyticity of these protocols allows insights into, for example, scalability, which are not present in the numerical results derived from control theoretic solutions.