Fractional ac Josephson effect in unconventional superconductors

Hyok Jon Kwon, K. Sengupta, Victor M. Yakovenko

Research output: Contribution to journalArticlepeer-review


For certain orientations of Josephson junctions between two p x-wave or two d-wave superconductors, the subgap Andreev bound states produce a 4π-periodic relation between the Josephson current I and the phase difference φ: I ∝ sin(φ/2). Consequently, the ac Josephson current has the fractional frequency eV / ℏ, where V is the dc voltage. In the tunneling limit, the Josephson current is proportional to the first power (not square) of the electron tunneling amplitude. Thus, the Josephson current between unconventional superconductors is carried by single electrons, rather than by Cooper pairs. The fractional ac Josephson effect can be observed experimentally by measuring frequency spectrum of microwave radiation from the junction.

Original languageEnglish (US)
Pages (from-to)814-822
Number of pages9
JournalFizika Nizkikh Temperatur (Kharkov)
Issue number7-8
StatePublished - Jul 2004
Externally publishedYes

ASJC Scopus subject areas

  • General Physics and Astronomy


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