Information Extraction from Decohering Systems via Indirect Continuous   Measurement
  In this article we discuss a general information extraction scheme to gain knowledge of the state and the amount of decoherence based on indirect continuous measurement. The purpose of this information extraction is to determine the feedback in order to control decoherence based on an ``output equation", described by a bilinear form. An interacting bilinear form of control system is used instead of master equation to analyze the dynamic properties of the system. The analysis of continuous measurement on a decohering quantum system has not been extensively studied before. 
Narayan Ganesan, Tzyh-Jong Tarn