On the Physical Realizability of a Class of Nonlinear Quantum Systems
  In this paper, the physical realizability property is investigated for a class of nonlinear quantum systems. This property determines whether a given set of nonlinear quantum stochastic differential equations corresponds to a physical nonlinear quantum system satisfying the laws of quantum mechanics. 
Aline I. Maalouf and Ian R. Petersen
math.OC quant-ph