  Quantum control theory is profitably reexamined from the perspective of
quantum information, two results on the role of quantum information technology
in quantum feedback control are presented and two quantum feedback control
schemes, teleportation-based distant quantum feedback control and quantum
feedback control with quantum cloning, are proposed. In the first feedback
scheme, the output from the quantum system to be controlled is fed back into
the distant actuator via teleportation to alter the dynamics of system. The
result theoretically shows that it can accomplish some tasks such as distant
feedback quantum control that Markovian or Bayesian quantum feedback can't
complete. In the second feedback strategy, the design of quantum feedback
control algorithms is separated into a state recognition step, which gives
"on-off" signal to the actuator through recognizing some copies from the
cloning machine, and a feedback (control) step using another copies of cloning
machine. A compromise between information acquisition and measurement
disturbance is established, and this strategy can perform some quantum control
tasks with coherent feedback.
