Macroscopic Quantum Tunneling of a Fluxon in a Long Josephson Junction

Takeo Kato, Masatoshi Imada

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48 Citations (Scopus)


Macroscopic quantum tunneling (MQT) for a single fluxon moving along a long Josephson junction is studied theoretically. To introduce a fluxon-pinning force, we consider inhomogeneities made by modifying thickness of an insulating layer locally. Two different situations are studied: one is the quantum tunneling from a metastable state caused by a single inhomogeneity, and the other is the quantum tunneling in a two-state system made by two inhomogeneities. In the quantum tunneling from a metastable state, the decay rate is estimated within the WKB approximation. Dissipation effects on a fluxon dynamics are taken into account by the Caldeira-Leggett theory. We propose a device to observe quantum tunneling of a fluxon experimentally. Required experimental resolutions to observe MQT of a fluxon seem attainable within the presently available micro-fabrication technique. For the two-state system, we study quantum resonance between two stable states, i.e., macroscopic quantum coherence (MQC). From the estimate for dissipation coefficients due to quasiparticle tunneling, the observation of MQC appears to be possible within the Caldeira-Leggett theory.

Original languageEnglish
Pages (from-to)2963-2975
Number of pages13
Journaljournal of the physical society of japan
Issue number9
Publication statusPublished - 1996
Externally publishedYes


  • Caldeira-Leggett theory
  • Dissipation
  • Fluxon
  • Long Josephson junction
  • Macroscopic quantum coherence
  • Macroscopic quantum tunneling
  • Sine-Gordon equation

ASJC Scopus subject areas

  • General Physics and Astronomy


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