The kinks, the solitons and the shocks in series connected discrete Josephson transmission lines

Abstract

We analytically study the localized running waves in the discrete Josephson transmission lines (JTL), constructed from Josephson junctions (JJ) and capacitors. The quasi-continuum approximation reduces calculation of the running wave properties to the problem of equilibrium of an elastic rod in the potential field. Making additional approximation, we reduce the problem to the motion of the fictitious Newtonian particle in the potential well. We show that there exist running waves in the form of supersonic kinks and solitons and calculate their velocities and profiles. We show that the nonstationary smooth waves which are small perturbations on the homogeneous non-zero background are described by Korteweg-de Vries equation, and those on zero background -- by modified Korteweg-de Vries equation. We also study the effect of dissipation on the running waves in JTL and find that in the presence of the resistors, shunting the JJ and/or in series with the ground capacitors, the only possible stationary running waves are the shock waves, whose profiles are also found. Finally in the framework of Stocks expansion we study the nonlinear dispersion and modulation stability in the discrete JTL.

Figures (7)

• Figure 1: Discrete JTL.
• Figure 2: The "potential energy" (\ref{['v100']}) (above) and the kink profile calculated with this energy according to Eq. (\ref{['v10']}) (below). We have chosen $\varphi_1=.5$.
• Figure 3: The "potential energy" (\ref{['v2']}) (above) and the soliton profile according to Eq. (\ref{['v10']}) (below). We have chosen $\varphi_1=1.$ and $\varphi_0=.5$.
• Figure 4: Discrete JTL with the capacitor and the resistor shunting the JJ and another resistor in series with the ground capacitor
• Figure 5: (above): The geometric property of the points belonging to the shaded region. (below): The phase space of the boundary conditions on the ends of the JTL $\varphi_1$ and $\varphi_2$. The region, which corresponds to the forbidden shock boundary conditions, is shaded.