Quantum rotator and Josephson junction: compact vs. extended phase and dissipative quantum phase transition

Edouard B. Sonin*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The paper reassesses the old dilemma “compact vs. extended phase” in the quantum theory of the rotator and the Josephson junction and the analogy of these two systems with a particle moving in a periodic potential. This dilemma is in fact the dilemma whether the states with the phases φ and φ + 2π are distinguishable, or not. In the past it was widely accepted that in the Josephson junction these states are distinguishable like for a particle moving in a periodic potential. This paper argues that the states with the phases φ and φ + 2π are indistinguishable as in a pendulum (a particular example of the quantum rotator). However, this does not lead to revision of the conclusions of the conventional theory predicting the transition from the superconducting to the insulating state in the small Josephson junction.

Original languageEnglish
Pages (from-to)450-463
Number of pages14
JournalFizika Nizkikh Temperatur
Volume48
Issue number5
DOIs
StatePublished - May 2022

Bibliographical note

Publisher Copyright:
© Edouard B. Sonin, 2022

Keywords

  • dissipative quantum phase transition
  • Josephson junction
  • quantum rotator

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