Decentralized coherent robust H∞ control of a class of large-scale uncertain linear complex quantum stochastic systems

This paper presents a procedure to synthesize a decentralized coherent robust H^∞ quantum controller for a class of large-scale uncertain linear complex quantum stochastic systems with a norm-bounded unstructured uncertainty. The H^∞ control objective is to obtain a strictly bounded real closed loop uncertain quantum system with a specified disturbance attenuation level g > 0. The main idea is that instead of treating the interconnections between quantum subsystems as uncertainties, we consider the neglected off-diagonal blocks of the transfer function matrix of the corresponding non-decentralized quantum controller as additional uncertainties. The resulting decentralized coherent quantum controller is required to satisfy a physical realizability condition.