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S Flach

Publications and source records attributed to S Flach.

33 records · Page 2Linked to original sources
PubMed2000

Observation of breathers in Josephson ladders.

We report on the observation of spatially localized excitations in a ladder of small Josephson junctions. The excitations are whirling states which persist under a spatially homogeneous force due to the bias current. These states of the ladder are visualized using a low temperature scanning laser microscopy. We also compute breather solutions with high accuracy in corresponding model equations. The stability analysis of these solutions is used to interpret the measured patterns in the I-V characteristics.

Journal Article↗
PubMed2000

ac-driven phase-dependent directed diffusion.

We study directed diffusion of a particle in a periodic symmetric potential under the influence of a time-periodic external field. The field lowers the symmetry of the phase space flow which results in directed diffusion even if the potential and the field are reflection symmetric. We analyze the interplay between broken symmetry and dynamical chaos.

Journal Article↗
PubMed1999

Moving lattice kinks and pulses: an inverse method.

We develop a general mapping from given kink or pulse shaped traveling-wave solutions including their velocity to the equations of motion on one-dimensional lattices which support these solutions. We apply this mapping-by definition an inverse method-to acoustic solitons in chains with nonlinear intersite interactions, nonlinear Klein-Gordon chains, reaction-diffusion equations, and discrete nonlinear Schrödinger systems. Potential functions can be found in a unique way provided the pulse shape is reflection symmetric and pulse and kink shapes are at least C2 functions. For kinks we discuss the relation of our results to the problem of a Peierls-Nabarro potential and continuous symmetries. We then generalize our method to higher dimensional lattices for reaction-diffusion systems. We find that increasing also the number of components easily allows for moving solutions.

Journal Article↗