Time-optimal quantum control of nonlinear two-level systems

Nonlinear two-level Landau-Zener type equations for systems with relevance for Bose-Einstein condensates and nonlinear optics are considered and the minimal time Tmin to drive an initial state to a given target state is investigated. Surprisingly, the nonlinearity may be canceled by a time-optimal unconstrained driving and Tmin becomes independent of the nonlinearity. For constrained and unconstrained driving explicit expressions are derived for Tmin, the optimal driving, and the protocol.