Optimizing fingerprinting experiments for parameter identification: Application to spin systems

We introduce the optimal fingerprinting process which is aimed at accurately identifying the parameters which characterize the dynamics of a physical system. A database is first built from the time evolution of an ensemble of dynamical systems driven by a specific field, which is designed by optimal control theory to maximize the efficiency of the recognition process. Curve fitting is then applied to enhance the precision of the identification. As an illustrative example, we consider the estimation of the relaxation parameters of a spin-1/2 particle. The experimental results are in good accord with the theoretical computations. We show on this example a physical limit of the estimation process.