  Quantum trajectory-based descriptions of interference between two coherent
stationary waves in a double-slit experiment are presented, as given by the de
Broglie-Bohm (dBB) and modified de Broglie-Bohm (MdBB) formulations of quantum
mechanics. In the dBB trajectory representation, interference between two
spreading wave packets can be shown also as resulting from motion of particles.
But a trajectory explanation for interference between stationary states is so
far not available in this scheme. We show that both the dBB and MdBB
trajectories are capable of producing the interference pattern for stationary
as well as wave packet states. However, the dBB representation is found to
provide the `which-way' information that helps to identify the hole through
which the particle emanates. On the other hand, the MdBB representation does
not provide any which-way information while giving a satisfactory explanation
of interference phenomenon in tune with the de Broglie's wave particle duality.
By counting the trajectories reaching the screen, we have numerically evaluated
the intensity distribution of the fringes and found very good agreement with
the standard results.
