Parallel InAs nanowires for Cooper pair splitters with Coulomb repulsion

TL;DR

This paper explores the use of parallel InAs nanowires with an epitaxial superconductor to enhance Cooper pair splitting efficiency, even with Coulomb repulsion, advancing potential quantum computing applications.

Contribution

It provides the first theoretical and experimental analysis of CPS in parallel InAs nanowires with Coulomb interaction, demonstrating improved splitting efficiency and potential for parafermionic states.

Findings

Significant CPS signal observed despite Coulomb repulsion.

Parallel nanowires enhance Cooper pair splitting efficiency.

Superconducting coupling dominates over inter-wire capacitance.

Abstract

Hybrid nanostructures consisting of two parallel InAs nanowires connected by an epitaxially grown superconductor (SC) shell recently became available. Due to the defect-free SC-semiconductor interface and the two quasi-one-dimensional channels being close by, these novel platforms can be utilized to spatially separate entangled pairs of electrons by using quantum dots (QD) in the so-called Cooper pair splitting (CPS) process. The minimized distance between the QDs overcomes the limitations of single-wire-based geometries and can boost the splitting efficiency. Here we investigate CPS in such a device, for the first time, where strong inter-dot Coulomb repulsion is also present and studied thoroughly. We analyze theoretically the slight reduction of the CPS efficiency imposed by the Coulomb interaction and compare it to the experiments. Despite the competition between crossed Andreev reflection (CAR) and inter-wire capacitance, a significant CPS signal is observed indicating the dominance of the superconducting coupling. Our results demonstrate that the application of parallel InAs nanowires with epitaxial SC is a promising route for the realization of parafermionic states relying on enhanced CAR between the wires.