https://doi.org/10.1140/epjb/e2015-50849-3
Regular Article
Quartets and the current-phase structure of a double quantum dot superconducting bijunction at equilibrium
1
Centre National de la Recherche Scientifique, Institut
NEEL, 38042
Grenoble Cedex 9,
France
2
Université Grenoble-Alpes, Institut NEEL,
38042
Grenoble Cedex 9,
France
3
Aix-Marseille Université, Université de Toulon, CNRS, CPT, UMR
7332, 13288
Marseille,
France
4
Laboratoire de Physique Théorique et des Hautes Energies, CNRS UMR
7589, Universités Paris 6 et 7, 4
place Jussieu, 75252
Paris Cedex 05,
France
a
e-mail: denis.feinberg@neel.cnrs.fr
Received: 10 December 2014
Received in final form: 3 March 2015
Published online: 13 April 2015
The equilibrium current-phase structure of a tri-terminal superconducting Josephson junction (bijunction) is analyzed as a function of the two relevant phases. The bijunction is made of two noninteracting quantum dots, each one carrying a single level. Nonlocal processes coupling the three terminals are described in terms of quartet tunneling and pair cotunneling. These couplings are due to nonlocal Andreev and cotunneling processes through the central superconductor S0, as well as direct interdot coupling. In some cases, two degenerate midgap Andreev states appear, symmetric with respect to the (π,π) point. The lifting of this degeneracy by interdot couplings induces a strong non-local inductance at low enough temperatures. This effect is compared to the mutual inductance of a two-loop circuit.
Key words: Mesoscopic and Nanoscale Systems
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2015