67 research outputs found
Magnetic field induced control of breather dynamics in a single plaquette of Josephson junctions
We present a theoretical study of inhomogeneous dynamic (resistive) states in
a single plaquette consisting of three Josephson junctions. Resonant
interactions of such a breather state with electromagnetic oscillations
manifest themselves by resonant current steps and voltage jumps in the
current-voltage characteristics. An externally applied magnetic field leads to
a variation of the relative shift between the Josephson current oscillations of
two resistive junctions. By making use of the rotation wave approximation
analysis and direct numerical simulations we show that this effect allows to
effectively control the breather instabilities, e. g. to increase (decrease)
the height of the resonant steps and to suppress the voltage jumps in the
current-voltage characteristics.Comment: 4 pages, 3 figure
Discrete breathers in dc biased Josephson-junction arrays
We propose a method to excite and detect a rotor localized mode
(rotobreather) in a Josephson-junction array biased by dc currents. In our
numerical studies of the dynamics we have used experimentally realizable
parameters and included self-inductances. We have uncovered two families of
rotobreathers. Both types are stable under thermal fluctuations and exist for a
broad range of array parameters and sizes including arrays as small as a single
plaquette. We suggest a single Josephson-junction plaquette as an ideal system
to experimentally investigate these solutions.Comment: 5 pages, 5 figure, to appear June 1, 1999 in PR
Spontaneous creation of discrete breathers in Josephson arrays
We report on the experimental generation of discrete breather states
(intrinsic localized modes) in frustrated Josephson arrays. Our experiments
indicate the formation of discrete breathers during the transition from the
static to the dynamic (whirling) system state, induced by a uniform external
current. Moreover, spatially extended resonant states, driven by a uniform
current, are observed to evolve into localized breather states. Experiments
were performed on single Josephson plaquettes as well as open-ended Josephson
ladders with 10 and 20 cells. We interpret the breather formation as the result
of the penetration of vortices into the system.Comment: 5 pages, 5 figure
Observation of breather-like states in a single Josephson cell
We present experimental observation of broken-symmetry states in a
superconducting loop with three Josephson junctions. These states are generic
for discrete breathers in Josephson ladders. The existence region of the
breather-like states is found to be in good accordance with the theoretical
expectations. We observed three different resonant states in the
current-voltage characteristics of the broken-symmetry state, as predicted by
theory. The experimental dependence of the resonances on the external magnetic
field is studied in detail.Comment: 7 pages, 8 figure
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