Physical limits and information bounds of micro control. I. Quantum filters and non-demolition measurements

The possible accuracy limit of micro control of dynamic systems in which the dominating disturbances are thermal and quantum noises is considered. The optimal control with a Kalman-Bucy filter (KBF) and physical limits of micro control of a macro object are studied. For the individual control of a micro object a quantum prototype of KBF with non-demolition observation on the basis of quantum filtering equation is introduced.