Template-assisted scalable nanowire networks

Topological qubits based on Majorana Fermions have the potential to revolutionize the emerging field of quantum computing by making information processing significantly more robust to decoherence. Nanowires are a promising medium for hosting these kinds of qubits, though branched nanowires are needed to perform qubit manipulations. Here we report a gold-free templated growth of III–V nanowires by molecular beam epitaxy using an approach that enables patternable and highly regular branched nanowire arrays on a far greater scale than what has been reported thus far. Our approach relies on the lattice-mismatched growth of InAs on top of defect-free GaAs nanomembranes yielding laterally oriented, low-defect InAs and InGaAs nanowires whose shapes are determined by surface and strain energy minimization. By controlling nanomembrane width and growth time, we demonstrate the formation of compositionally graded nanowires with cross-sections less than 50 nm. Scaling the nanowires below 20 nm leads to the formation of homogeneous InGaAs nanowires, which exhibit phase-coherent, quasi-1D quantum transport as shown by magnetoconductance measurements. These results are an important advance toward scalable topological quantum computing.Authors from EPFL and U. Basel acknowledge funding through the NCCR QSIT. Authors from EPFL further thank funding from SNF (project no. IZLRZ2-163861) and H2020 via the ITN project INDEED. Work at U. Basel was partially supported by the Swiss NSF, and the Swiss Nanoscience Institute SNI. S.M.S. acknowledges funding from “Programa Internacional de Becas “la Caixa″-Severo Ochoa”. J.A. and S.M.S. acknowledge funding from Generalitat de Catalunya 2017 SGR 327 and the Spanish MINECO coordinated project ValPEC (ENE2017-85087-C3). ICN2 acknowledges support from the Severo Ochoa Programme (MINECO, grant no. SEV2013-0295) and is funded by the CERCA Programme/Generalitat de Catalunya. This work has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement no. 654360 NFFA-Europe. V.G.D. thanks the Ministry of Education and Science of the Russian Federation for financial support under grant no. 14-613-21-0055 (project ID RFMEFI61316 × 0055). L.J.L. acknowledges support of NSF DMR-1611341. M.O.H. acknowledges support of the NSF GRFP. NUCAPT received support from the MRSEC program (NSF DMR-1720139) at the Materials Research Center, the SHyNE Resource (NSF ECCS-1542205), and the Initiative for Sustainability and Energy (ISEN) at Northwestern University.Peer reviewe