  In this paper, we consider stochastic master equations describing the
evolution of quantum spin-1/2 systems interacting with electromagnetic fields
undergoing continuous-time measurements. We suppose that the initial states and
the exact values of the physical parameters are unknown. We prove that the
feedback stabilization strategy considered in [16] is robust to these
imperfections. This is shown by studying the asymptotic behavior of the coupled
stochastic master equations describing the evolutions of the actual state and
the estimated one under appropriate assumptions on the feedback controller. We
provide sufficient conditions on the feedback controller and a valid domain of
estimated parameters which ensure exponential stabilization of the coupled
system. Furthermore, our results allow us to answer positively to
[15,Conjecture 4.4] in the case of spin-1/2 systems with unknown initial
states, even in presence of imprecisely known physical parameters.
