  Two infinite, two-dimensional, lattice, free fermion systems, initially in
different invariant states, are allowed to communicate via two point contacts,
through which direct tunneling of fermions takes place. Calculations of the
local particle-density and of the local particle-currents distributions,
performed in the final stationary state, exhibit neat interference patterns.
Their dependence on the interaction details is discussed on examples. The local
density and local currents are shown to be correlated.
