Dynamics of fluxons in Josephson junctions under the noise current action

The motion of magnetic flux quanta (fluxons) in long Josephson junctions (L JJ) under action of direct and random currents is under investigation. The velocity distribution function of fluxons is calculated which, even in the absence of the direct current component, is non-Gaussian. As a consequence, the current-voltage characteristic of a noise junction differs from that f or a regular one. The dependence of the voltage difference on the current f or junctions, both with and without the noisy current component, is shown t o be nonmonotonic. There is a good agreement between the calculation data a nd the numerical simulation results. (C) 2000 MAIK "Nauka/Interperiodica".