Quantum Filtering (Quantum Trajectories) for Systems Driven by Fields in   Single Photon States and Superposition of Coherent States
  We derive the stochastic master equations, that is to say, quantum filters, and master equations for an arbitrary quantum system probed by a continuous-mode bosonic input field in two types of non-classical states. Specifically, we consider the cases where the state of the input field is a superposition or combination of: (1) a continuous-mode single photon wave packet and vacuum, and (2) any number of continuous-mode coherent states. 
J.E. Gough, M.R. James, H.I. Nurdin and Joshua Combes
quant-ph cs.SY math.OC