  The dynamics of a non-Markovian open quantum system described by a general
time-local master equation is studied. The propagation of the density operator
is constructed in terms of two processes: (i) deterministic evolution and (ii)
evolution of a probability density functional in the projective Hilbert space.
The analysis provides a derivation for the jump probabilities used in the
recently developed non-Markovian quantum jump (NMQJ) method (Piilo et al 2008
Phys. Rev. Lett. 100 180402).
