In-plane selective area InSb-Al nanowire quantum networks

TL;DR

This paper presents a novel in-plane selective-area growth method for InSb-Al nanowire networks that exhibit excellent quantum transport properties, enabling potential applications in topological quantum computing.

Contribution

It introduces a new growth technique for defect-free InSb-Al nanowire networks with superior quantum transport characteristics on mismatched substrates.

Findings

Demonstrated phase-coherent transport up to 10 μm

Achieved a hard superconducting gap with 2e-periodic Coulomb oscillations

Realized defect-free nanowire networks suitable for topological quantum computing

Abstract

Strong spin-orbit semiconductor nanowires coupled to a superconductor are predicted to host Majorana zero modes. Exchange (braiding) operations of Majorana modes form the logical gates of a topological quantum computer and require a network of nanowires. Here, we develop an in-plane selective-area growth technique for InSb-Al semiconductor-superconductor nanowire networks with excellent quantum transport properties. Defect-free transport channels in InSb nanowire networks are realized on insulating, but heavily mismatched InP substrates by 1) full relaxation of the lattice mismatch at the nanowire/substrate interface on a (111)B substrate orientation, 2) nucleation of a complete network from a single nucleation site, which is accomplished by optimizing the surface diffusion length of the adatoms. Essential quantum transport phenomena for topological quantum computing are demonstrated in these structures including phase-coherent transport up to 10 $\mu$m and a hard superconducting gap accompanied by 2$e$-periodic Coulomb oscillations with an Al-based Cooper pair island integrated in the nanowire network.