Fast route to equilibration

We present a control scheme for quantum systems coupled to a thermal bath. We demonstrate state-to-state control between two Gibbs states. This scheme can be used to accelerate thermalization and cool the open system. Starting from a microscopic description, we derive the reduced system dynamics, leading to a nonadiabatic master equation. The equation contains nontrivial effects due to the nonadiabatic driving and bath interaction. These special features enable controlling the open system and accelerating the entropy changes. For a two-level system model, we obtain a general solution and introduce a reverse-engineering scheme for control. The control problem is analyzed in the context of the theory of quantum control and the accompanying thermodynamic cost.