Enhanced crossed Andreev reflection in a superconducting ladder

Andreev reflection is a process that happens at the junction of a normal metal (NM) and a superconductor(SC), where the Cooper-pair current in the superconductor gets equal contributions from the electron and hole channels of the normal metal. Crossed Andreev reflection (cAr) is a related process that happens in a system of two NM's independently connected to a SC when the current in the electron channel of the first NM and the current in the hole channel of the second NM together contribute to the Cooper-pair current in the SC. A typical experimental set-up to investigate cAr consists of two ferromagnetic metal leads connected to an s-wave superconductor. We propose an alternative mesoscopic set-up that enhances cAR which contains no ferromagnetic parts. Instead, our set-up consists of two NM's coupled to a superconducting ladder. We calculate the currents in the different channels and demonstrate enhanced cAr.