Bohmian versus semiclassical description of interference phenomena

The quantum trajectory method is without doubt an intriguing formulation of time-dependent quantum mechanics. Its most attractive feature is the concept of quantum trajectories, along with its apparent similarity to semiclassical theory. However, apart from these seemingly classical features the Bohmian flow differs dramatically from that of classical mechanics. The analysis presented shows the dramatic role of the quantum potential in systems where the underlying classical dynamics is dominated by focal points or caustics. Crossing of the quantum trajectories is prevented through application of steep force fields, and the resulting distribution of trajectories leads to the correct probability density without the cross terms required in the semiclassical solution.