Design aspects of superconducting-phase quantum bits

Gianni Blatter, Vadim B. Geshkenbein, Vadim B. Geshkenbein, Lev Ioffe, Lev B. Ioffe

Research output: Contribution to journalArticle

158 Scopus citations


A superconducting-phase quantum bit (qubit) involves three or more Josephson junctions combined into a superconducting loop and defines one of the promising solid-state device implementations for quantum computing. Recently, so called π junctions, Josephson junctions with a ground state characterized by a π-phase shift across, have attracted much attention. We show how to make use of such π junctions in the construction of superconducting phase qubits and discuss the advantage over conventional designs based on magnetically frustrated loops. Starting from a basic five-junction loop with one π junction, we show how to construct effective junctions with degenerate minima characterized by phase shifts 0 and π and superconducting-phase switches. These elements are then combined into a superconducting-phase qubit which operates exclusively with switches, thus avoiding permanent contact with the environment through external biasing. The resulting superconducting-phase qubits can be understood as the macroscopic analog of the "quiet" s-wave-d-wave-s-wave Josephson-junction qubits introduced by Ioffe et al.

Original languageEnglish (US)
Article number174511
Pages (from-to)1745111-1745119
Number of pages9
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number17
Publication statusPublished - Jan 1 2001


All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Blatter, G., Geshkenbein, V. B., Geshkenbein, V. B., Ioffe, L., & Ioffe, L. B. (2001). Design aspects of superconducting-phase quantum bits. Physical Review B - Condensed Matter and Materials Physics, 63(17), 1745111-1745119. [174511].