Rapid control of two-qubit systems based on measurement feedback
Xiaqing Sun, Sen Kuang, Daoyi Dong · 2017
For two-qubit systems with a degenerate measurement operator, this paper presents a control approach to achieve rapid stabilization to a target Bell state. This approach uses two control channels where the control laws associated with these two channels are designed as a constant and a switching control law, respectively. In the control scheme, the system state space is divided into two parts: the set containing the target state, and its complementary set. We design corresponding control laws in these two sets via different Lyapunov functions. In this scheme, the system trajectory switches only one or two times between the two sets and the convergence rate to the target state can be improved. We provide the conditions on the control Hamiltonians to stabilize the target state by analyzing the stability of the closed-loop system.