Cooper-pair splitting in two parallel InAs nanowires

TL;DR

This study demonstrates Cooper-pair splitting between two parallel InAs nanowires coupled to a superconductor, revealing inter-wire interactions and transport phenomena relevant for topological quantum states.

Contribution

First experimental realization of inter-wire Cooper-pair splitting in parallel nanowires, advancing the understanding of topological superconductivity.

Findings

Detected correlated currents indicating Cooper-pair splitting

Observed transport resonances in the superconducting state

Demonstrated inter-wire interaction mediated by a superconductor

Abstract

We report on the fabrication and electrical characterization of an InAs double - nanowire (NW) device consisting of two closely placed parallel NWs coupled to a common superconducting electrode on one side and individual normal metal leads on the other. In this new type of device we detect Cooper-pair splitting (CPS) with a sizeable efficiency of correlated currents in both NWs. In contrast to earlier experiments, where CPS was realized in a single NW, demonstrating an intrawire electron pairing mediated by the superconductor (SC), our experiment demonstrates an inter- wire interaction mediated by the common SC. The latter is the key for the realization of zero-magnetic field Majorana bound states, or Parafermions; in NWs and therefore constitutes a milestone towards topological superconductivity. In addition, we observe transport resonances that occur only in the superconducting state, which we tentatively attribute to Andreev Bound states and/or Yu-Shiba resonances that form in the proximitized section of one NW.