Intrinsic localisation in the dynamics of a Josephson-junction ladder

Floría, L. M.; Marín, J. L.; Martínez, Pedro J.; Falo, Fernando; Aubry, S.

doi:10.1209/epl/i1996-00266-0

Cited by 70 publications

(66 citation statements)

References 17 publications

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“…2. We observe a localized whirling state expected for a DB, namely a rotobreather [10]. In this case 2 vertical junctions and 4 horizontal junctions of the DB are rotating, with all others remaining in the superconducting state.…”

Section: π φ0mentioning

confidence: 72%

“…Experiments on localization of light propagating in weakly coupled optical waveguides [7], low-dimensional crystals [8] and antiferromagnetic materials [9] have been recently reported. In this work we realize the theoretical proposal [10] to observe DB-like localized excitations in arrays of coupled Josephson junctions. A Josephson junction is formed between two superconducting islands.…”

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confidence: 95%

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Observation of Breathers in Josephson Ladders

et al. 2000

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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.The present decade has been marked by an intense theoretical research on dynamical localization phenomena in spatially discrete systems, namely on discrete breathers (DB). These exact solutions of the underlying equations of motion are characterized by periodicity in time and localization in space. Away from the DB center the system approaches a stable (typically static) equilibrium. (For reviews see [1], [2]). These solutions are robust to changes of the equations of motion, exist in translationally invariant systems and any lattice dimension. Discrete breathers have been discussed in connection with a variety of physical systems such as large molecules, molecular crystals [3], spin lattices [4,5], to name just a few.For a localized excitation such as a DB, the excitation of plane waves which might carry the energy away from the DB does not occur due to the spatial discreteness of the system. The discreteness provides a cutoff for the wave length of plane waves and thus allows to avoid resonances of all temporal DB harmonics with the plane waves. The nonlinearity of the equations of motion is needed to allow for the tuning of the DB frequency [1].Though the DB concept was initially developed for conservative systems, it can be easily extended to dissipative systems [6]. There discrete breathers become timeperiodic spatially localized attractors, competing with other (perhaps nonlocal) attractors in phase space. The characteristic property of DBs in dissipative systems is that these localized excitations are predicted to persist under the influence of a spatially homogeneous driving force. This is due to the fact, that the driving force compensates the dissipative losses of the DB.So far research in this field was predominantly theoretical. Identifying and analyzing of experimental systems for the direct observation of DBs thus becomes a very actual and challenging problem. Experiments on localization of light propagating in weakly coupled optical waveguides [7], low-dimensional crystals [8] and antiferromagnetic materials [9] have been recently reported. In this work we realize the theoretical proposal [10] to observe DB-like localized excitations in arrays of coupled Josephson junctions. A Josephson junction is formed between two superconducting islands. Each island is characterized by a macroscopic wave function Ψ ∼ e iθ of the superconducting state. The dynamics of the junction is described by the time evolution of the gauge-invariant phase difference ϕ = θ 2 − θ 1 − 2π Φ0A · ds between adjacent islands. H...

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Section: π φ0mentioning

confidence: 72%

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confidence: 95%

Observation of Breathers in Josephson Ladders

et al. 2000

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“…Here the shifts in the overtone spectrum could be accounted for, in a quantitative manner, by a nonlinear coupling of the amide I mode to optical phonons [7,6]. Finally, following a proposal by Floría et al [8], localized excitations in Josephson junction ladders have been detected in I/V curves [3] and visualized by laser microscopy [4].…”

Section: Introductionmentioning

confidence: 89%

Breathers in systems with intrinsic and extrinsic nonlinearities

Cruzeiro

Eilbeck

Marín

et al. 2000

Physica D: Nonlinear Phenomena

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We study the interplay between nonlinearity and localization in a model consisting of a quantum quasiparticle interacting with a nonlinear extended lattice. The isolated lattice can support discrete breathers, and the coupling of the quasiparticle to the lattice leads to localized quasiparticle states. Minimum energy states of the full system can have both a breather and a solitonic character. Excited states lead to interesting new phenomena, such as full breather states, which arise from the combination of intrinsic and extrinsic nonlinearity.

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“…Another experimental system, in which the K parameter is reasonably well controlled is a two-parallel array of JJ's ͑a ladder͒. 16 Although the dynamical behavior of vortex does not follow the discrete sine-Gordon equation, preliminary computer simulations confirm the validity of the above results.…”

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confidence: 85%