Three-terminal superconductor (S) - normal metal (N) - superconductor (S) Josephson junctions are investigated. In a geometry where a T-shape normal metal is connected to three superconducting reservoirs, new sub-gap structures appear in the differential resistance for specific combinations of the superconductor chemical potentials. Those correspond to a correlated motion of Cooper pairs within the device that persist well above the Thouless energy and is consistent with the prediction of quartets formed by two entangled Cooper pairs. A simplified nonequilibrium Keldysh Green's function calculation is presented that supports this interpretation.
@article{arxiv.1307.4862,
title = {Sub-Gap Structure in the Conductance of a Three-Terminal Josephson Junction},
author = {Andreas H. Pfeffer and Jean Eudes Duvauchelle and Hervé Courtois and Régis Mélin and Denis Feinberg and François Lefloch},
journal= {arXiv preprint arXiv:1307.4862},
year = {2014}
}