Welcher Weg? A trajectory representation of a quantum Young's   diffraction experiment
  The double slit problem is idealized by simplifying each slit by a point source. A composite reduced action for the two correlated point sources is developed. Contours of the reduced action, trajectories and loci of transit times are developed in the region near the two point sources. The trajectory through any point in Euclidian 3-space also passes simultaneously through both point sources. 
Edward R. Floyd