25 avenue des martyrs - Grenoble
Nanowire-based structures for applications in quantum information processing
Thomas Schäpers (Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Germany)
Nanowires are not only interesting as building blocks for future nanoelectronic device applications they are also very promising candidates for realizing circuits for quantum information processing. Here, two major directions can be identified. First, nanowires can be employed to create Majorana fermions for robust topological quantum computing. One essential prerequisite is the verification of spin helical transport. In quantum point contacts based on InAs nanowires we achieved ballistic transport with quantized conductance. At the last step a dip feature is observed which is attributed to the presence of helical states . The emergence of this dip feature is explained in the framework of exchange interactions. Recently, our research towards topological quantum computation is extended by using nanowires based on topological insulators such as Bi2Te3 or Sb2Te3. As a second option for applications in quantum information, semiconductor nanowires are also interesting for gate-controlled Josephson junctions in transmon qubits. In order to optimize the junction performance, the InAs nanowire is covered in-situ by a superconducting Al or Nb shell. These junctions are subsequently integrated in a superconducting resonator circuit.
Work done in collaboration with : D. Grützmacher, Y. Günel, N. Güsken, A. R. Jalil, J. Kölzer, S. Heedt, M. Lepsa, G. Mussler, T. Rieger, D. Rosenbach, J. Schubert, P. Schüffelgen, S. Trellenkamp, Ch. Weyrich, P. Zellekens (Jülich), N. Traverso Ziani, F. Crepin, B. Trauzettel (University of Würzburg), F. W. Prost (University Duisburg-Essen), M. Weides, S. Schlör (KIT Karlsruhe).
 S. Heedt, N. T. Ziani, F. Crepin, W. Prost, S. Trellenkamp, J. Schubert, D. Grützmacher, B. Trauzettel, Th. Schäpers, Nature Physics, 13, 563 (2017). doi:10.1038/nphys4070
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