Effect of feedback on the control of a two-level dissipative quantum   system
  We show that it is possible to modify the stationary state by a feedback control in a two-level dissipative quantum system. Based on the geometric control theory, we also analyze the effect of the feedback on the time-optimal control in the dissipative system governed by the Lindblad master equation. These effects are reflected in the function $\Delta_A(\vec{x})$ and $\Delta_B(\vec{x})$ that characterize the optimal trajectories, as well as the switching function $\Phi(t)$ and $\theta(t),$ which characterize the switching point in time for the time-optimal trajectory. 
L. C. Wang, X. L. Huang, X. X. Yi