  The experimental results of Kocsis et al., Mahler et al. and the proposed
experiments of Morley et al. show that it is possible to construct
"trajectories" in interference regions in a two-slit interferometer. These
results call for a theoretical re-appraisal of the notion of a "quantum
trajectory" first introduced by Dirac and in the present paper we re-examine
this notion from the Bohm perspective based on Hamiltonian flows. In
particular, we examine the short-time propagator and the role that the quantum
potential plays in determining the form of these trajectories. These
trajectories differ from those produced in a typical particle tracker and the
key to this difference lies in the active suppression of the quantum potential
necessary to produce Mott-type trajectories. We show, using a rigorous
mathematical argument, how the active suppression of this potential arises.
Finally we discuss in detail how this suppression also accounts for the quantum
Zeno effect.
