Thermal hopping and retrapping of a Brownian particle in the tilted   periodic potential of a NbN/MgO/NbN Josephson junction
  We report on the occurrence of multiple hopping and retrapping of a Brownian particle in a tilted washboard potential. The escape dynamic has been studied experimentally by measuring the switching current distributions as a function of temperature in a moderately damped NbN/MgO/NbN Josephson junction. At low temperatures the second moment of the distribution increases in agreement with calculations based on Kramers thermal activation regime. After a turn-over temperature T*, the shape of the distributions starts changing and width decreases with temperature. We analyze the data through fit of the switching probability and Monte Carlo simulations and we find a good agreement with a model based on a multiple retrapping process. 
Luigi Longobardi, Davide Massarotti, Giacomo Rotoli, Daniela   Stornaiuolo, Gianpaolo Papari, Akira Kawakami, Giovanni Piero...
cond-mat.supr-con