Observation of breather resonances in Josephson ladders

Abstract

We report experimental observation of resonances excited by nonlinear localized states (rotobreathers) in Josephson junction ladders. The rotobreathers are found to persist in a frequency range that allows for their resonant interaction with linear electromagnetic modes in the ladders. This interaction leads to nearly constant voltage steps on the current-voltage characteristics. We also present numerical simulations that agree well with experimental data and confirm the resonant interaction between breathers and linear waves. Resonances occur at the base frequency as well as higher harmonics of the linear modes. The observed substructures on the resonances are attributed to the cavity modes for the ladders. Both experimental and simulated current-voltage characteristics show good quantitative agreement with an analytically calculated dispersion relation for linear electromagnetic modes.

Discrete breathers — Advances in theory and applications

“…58) showed very good qualitative agreement with experiments [361]. In addition numerical studies allow one to directly access the tricky details of the nonlinear dynamics of the obtained states.…”

Breathers in a single plaquette of Josephson junctions: existence, stability and resonances

“…Moreover, a breather state may be tuned into resonance with other dynamical modes of the system which leads to an increasing complexity of the breather dynamics. Experimental studies revealed a whole "zoo" of different breather states, instabilities, resonances and switching scenarios depending on the parameters of the ladder [7][8][9][10][11]. Similar features have been found in numerical simulations.…”

“…The I -V characteristics of a breather (11) differs from that of the HWS which is γ = Vα. The breather is characterized by a smaller voltage drop across the resistive vertical junction for a given current value γ .…”

“…Discrete breathers were detected experimentally in different systems, e.g. in weakly coupled optical waveguides [4], in the lattice dynamics of solids [5], in antiferromagnets [6] and in systems of interacting Josephson junctions [7][8][9][10][11].…”

Discrete breathers in Josephson arrays

“…After these works more experiments were done and the results reported on various publications. [12][13][14][15][16][17] Experiments at MIT 2 were done in open ladders with nine vertical junctions ͑see Fig. 6͒.…”