Understanding degenerate ground states of a protected quantum circuit in the presence of disorder

Joshua M. Dempster, Bo Fu, David G. Ferguson, D. I. Schuster, Jens Koch

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

A recent theoretical proposal suggests that a simple circuit utilizing two superinductors may produce a qubit with ground-state degeneracy [Brooks, Phys. Rev. A 87, 052306 (2013)PLRAAN1050-294710.1103/PhysRevA.87.052306]. We perform a full circuit analysis along with exact diagonalization of the circuit Hamiltonian to elucidate the nature of the spectrum and low-lying wave functions of this 0-π device. We show that the ground-state degeneracy is robust to disorder in charge, flux, and critical current as well as insensitive to modest variations in the circuit parameters. Our treatment is nonperturbative, provides access to excited states and matrix elements, and is immediately applicable also to intermediate parameter regimes of experimental interest.

Original languageEnglish (US)
Article number094518
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume90
Issue number9
DOIs
StatePublished - Sep 24 2014

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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