H∞ filter design for quantum stochastic systems

This paper is concerned with the H_infin filtering problem for a class of noncommutative linear stochastic systems, among which quantum technology has been well recognized to be a typical example. A new structure of slack variables is introduced to solve the H_infin filtering problem which gives a sufficient condition for the existence of desired H_infin filters for quantum systems in terms of linear matrix inequalities (LMIs). Two examples from quantum optics are given to show the effectiveness of the proposed approach.