Decoherence and fluctuations in quantum interference experiments

We analyze the notion of quantum coherence in an interference experiment. W e let the phase shifts fluctuate according to a given statistical distribut ion and introduce a decoherence parameter, defined in terms of a generalize d visibility of the interference pattern. One might naively expect that a p article ensemble suffers a greater loss of quantum coherence by interacting with an increasingly randomized distribution of shifts. As we shall see, t his is not always true.