Dynamics of Josephson Junction under “Green” Noise

The stochastic dynamics of the Josephson junction is studied when external noise is nonwhite and high-pass filtered (“green” noise). In this case the diffusion coefficient of the Fokker-Planck equation is zero. Therefore the phase locking between the wave functions of the Cooper pairs is described and interpreted by the Krylov-Bogoljubov averaging method. The maximum (“critical”) Josephson current is redefined. Nonlinear diffusion and the lifetime of the phase locking of wave functions are considered. Background illumination, zero-point fluctuations and filtered white noise are used as examples of green noise. It is shown that the effect of green noise on the superconducting state of the junction is much less destructive than that of white one.