Superposition principle, spontaneous decoherence and C60molecule interference

A coherent superposition of two Gaussian wavepackets, which freely evolves in time, gives rise to an interference pattern similar to that of the single-particle double-slit Young's experiment. In this paper we show that fringe visibility can be reduced by spontaneous decoherence, which can also destroy quantum coherence when interaction between a system and its surroundings can be neglected. This decoherence is due to fluctuations in the evolution time and, in general, cannot be achieved when simple classical averages are considered. We compare our theoretical results with a C 60 fullerenes interference experiment, where thermal decoherence is not relevant, but the fringe visibility is actually reduced.