RARE EVENTS IN QUANTUM TUNNELING

Small fluctuations of a potential barrier can generate very large fluc tuations of the quantum tunneling transmission. The statistical proper ties of the tunneling transmission exhibit a rich behaviour associated to long-tail distributions. The large fluctuations modify the scaling properties of the tunneling transmission with the sample size. In som e cases tunneling is dominated by the very few most probable paths. Th ese large fluctuations can be relevant for electron transport through thin tunnel junctions or through complex systems.