Performance Analysis and Coherent Guaranteed Cost Control for Uncertain   Quantum Systems
  This paper presents several results on performance analysis for a class of uncertain linear quantum systems subject to either quadratic or non-quadratic perturbations in the system Hamiltonian. Also, coherent guaranteed cost controllers are designed for the uncertain quantum systems to achieve improved control performance. The coherent controller is realized by adding a control Hamiltonian to the quantum system and its performance is demonstrated by an example. 
Chengdi Xiang, Ian R. Petersen and Daoyi Dong
quant-ph cs.SY