Exact solutions to a nonlinear Schrödinger lattice with a saturable nonlinearity are reported. For finite lattices we find two different standing-wave-like solutions, and for an infinite lattice we find a localized soliton-like solution. The existence requirements and stability of these solutions are discussed, and we find that our solutions are linearly stable in most cases. We also show that the effective Peierls-Nabarro barrier potential is nonzero thereby indicating that this discrete model is quite likely nonintegrable.

We report on a systematic investigation of the properties of long Josephson junctions under the application of magnetic fields generating Fiske and Eck steps in the current-voltage characteristics. Numerical data and experimental results are compared with a cavity mode-based model predicting the voltage position and the amplitude of the current singularities. The comparison shows that this model can account for the shape and for the maximum current modulation of the singularities when the field penetration overcomes Meissner shielding above the value H0=2λjjc

No abstract

No abstract

We investigate both analytically and numerically phase locking and flux-flow resonances of long Josephson junctions in the presence of homogeneous microwave fields. We use a power balance analysis and a perturbation expansion around the uniform rotating solution to derive analytical expressions for IV curves. The dependence of the flux-flow step on the amplitude of the rf field and the appearance of satellite steps are explained. As a result we show that satellite steps around the main flux-flow resonance are spaced by both odd and even harmonics of the rf frequency. An analytical expression for the locking range in current of the phase-lock steps is also derived. These results are found to be in good agreement with numerical results.