Transient dynamics in driven long Josephson junctions.

The switching time from the superconductive metastable state of a long Josephson junction (LJJ)[1] is computationally analyzed in the framework of the perturbed sine-Gordon equation. The model includes an external bias current term and a stochastic noise source, i.e. a Lévy noise term. The effects of this noise on the mean escape time (MET) from the superconductive state are analyzed. The investigation is performed by considering a wide range of values of system parameters and different noise statistics: Gaussian, Cauchy-Lorentz and Lévy-Smirnov[2]. We found evidence of well known noise induced phenomena on the MET behavior, that is the noise enhanced stability (NES) and resonant activation (RA). Furthermore, the action of the noise source and oscillating bias current on the soliton motion[3] is deeply analyzed. Finally, we take into account a different, more realistic, bias current configuration, by considering an inhomogeneous current density through the junction. Differences in the soliton dynamics are also found in this case. 1. G. Augello, D. Valenti, and B. Spagnolo, Eur. Phys. J. B 70, 145 (2009). 2. G. Augello, D. Valenti, and B. Spagnolo, Eur. Phys. J. B 78, 225 (2010). 3. A. V. Ustinov, Physica D 123, 315 (1998); D. W. McLaughlin, and A. C. Scott, Phys. Rew. A 18, 1652 (1978).