Decoherence demystified : The hydrodynamic viewpoint

The hydrodynamic formulation of quantum mechanics is used to elucidate the mechanism for decoherence, the suppression of interference effects in a system evolving from an initial coherent superposition. Analysis of time-dependent trajectory ensembles, flux maps, and elements of the stress tensor for two composite systems, in one of which the system is uncoupled to the environment, leads to the decoherence mechanism. For the uncoupled case, the quantum force acting on the fluid elements directs flux toward an attractor where the interference feature arises. For the coupled case, the classical force acting on each fluid element counters the quantum force and leads to gradual separation of the components of the initial superposition. Concomitantly, fluid stress is relieved when flux vectors diverge from a repellor in the mid-region between the separating wavepackets, thus suppressing formation of the interference feature.