Identifying a Two-State Hamiltonian in the Presence of Decoherence
  Mapping the system evolution of a two-state system allows the determination of the effective system Hamiltonian directly. We show how this can be achieved even if the system is decohering appreciably over the observation time. A method to include various decoherence models is given and the limits of this technique are explored. This technique is applicable both to the problem of calibrating a control Hamiltonian for quantum computing applications and for precision experiments in two-state quantum systems. For simple models of decoherence, this method can be applied even when the decoherence time is comparable to the oscillation period of the system. 
Jared H. Cole, Andrew D. Greentree, Daniel K. L. Oi, Sonia G.   Schirmer, Cameron J. Wellard and Lloyd C. L. Hollenberg