Feedback control of linear quantum optical systems

This paper studies feedback quantum control of a class of linear quantum optical systems by means of squeezing and phase modulation. A new quadrature representation of such systems is introduced, which includes explicitly phase modulation of light fields involved. Some fundamental relations are derived in terms of the new quadrature representation. The coherent quantum LQG control studied in is re-investigated base on controller parametrization and a two-stage optimization approach. Examples are given to illustrate the effectiveness of the results in the paper.