Spin-resolved Andreev levels and parity crossings in hybrid superconductor-semiconductor nanostructures
| Autor: | Lee, Eduardo J. H., Jiang, Xiaocheng, Houzet, Manuel, Aguado, Ramon, Lieber, Charles M., De Franceschi, Silvano |
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| Rok vydání: | 2013 |
| Předmět: | |
| Zdroj: | Nature Nanotech., 9 (2014) 79-84 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1038/nnano.2013.267 |
| Popis: | The hybrid combination of superconductors and low-dimensional semiconductors offers a versatile ground for novel device concepts, such as sources of spin-entangled electrons, nanoscale superconducting magnetometers, or recently proposed qubits based on topologically protected Majorana fermions. The underlying physics behind such hybrid devices ultimately rely on the magnetic properties of sub-gap excitations, known as Andreev levels. Here we report the Zeeman effect on the Andreev levels of a semiconductor nanowire quantum dot (QD) strongly coupled to a conventional superconductor. The combination of the large QD g-factor with the large superconductor critical magnetic field allows spin degeneracy to be lifted without suppressing superconductivity. We show that a Zeeman-split Andreev level crossing the Fermi energy signals a quantum phase transition in the ground state of the superconductivity-induced QD, denoting a change in the fermionic parity of the system. This transition manifests itself as a zero-bias conductance anomaly appearing at a finite magnetic field, with properties that resemble those expected for Majorana fermions in a topological superconductor. Although the herein reported zero-bias anomalies do not hold any relation with topological superconductivity, the observed parity transitions can be regarded as precursors of Majorana modes in the long-wire limit. Comment: 16 pages, 9 figures |
| Databáze: | arXiv |
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