Lee, Eduardo J. H.Jiang, XiaochengHouzet, ManuelAguado, RamónLieber, CharlesDe Franceschi, Silvano2015-09-142013Lee, Eduardo J. H., Xiaocheng Jiang, Manuel Houzet, Ramón Aguado, Charles M. Lieber, and Silvano De Franceschi. 2013. “Spin-Resolved Andreev Levels and Parity Crossings in Hybrid Superconductor–semiconductor Nanostructures.” Nature Nanotechnology 9 (1) (December 15): 79–84. doi:10.1038/nnano.2013.267.1748-3387http://nrs.harvard.edu/urn-3:HUL.InstRepos:22556449The physics and operating principles of hybrid superconductor–semiconductor devices rest ultimately on the magnetic properties of their elementary subgap excitations, usually called Andreev levels. Here we report a direct measurement of the Zeeman effect on the Andreev levels of a semiconductor quantum dot with large electron g-factor, strongly coupled to a conventional superconductor with a large critical magnetic field. This material combination allows spin degeneracy to be lifted without destroying superconductivity. We show that a spin-split Andreev level crossing the Fermi energy results in a quantum phase transition to a spin-polarized state, which implies a change in the fermionic parity of the system. This crossing manifests itself as a zero-bias conductance anomaly at finite magnetic field with properties that resemble those expected for Majorana modes in a topological superconductor. Although this resemblance is understood without evoking topological superconductivity, the observed parity transitions could be regarded as precursors of Majorana modes in the long-wire limit.en-USJournal Article2015-08-12E. Lee, X. Jiang, M. Houzet, R. Aguado, C.M. Lieber, and S. De Franceschi2015-09-1410.1038/nnano.2013.267