Signatures of interaction-induced helical gaps in nanowire quantum point contacts

• Published in: Nature physics Vol. 13; no. 6; pp. 563 - 567
• Main Authors: Heedt, S., Traverso Ziani, N., Crépin, F., Prost, W., Trellenkamp, St, Schubert, J., Grützmacher, D., Trauzettel, B., Schäpers, Th
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.06.2017; Nature Publishing Group; Nature Publishing Group [2005-....]
• Subjects: 142/126; 639/766/1130/2798; 639/766/119/1000/1016; 639/766/119/1001; 639/766/483/640; 639/925/927/1007; Asymmetry; Atomic; Behavior; Classical and Continuum Physics; Complex Systems; Condensed Matter Physics; Conductance; Devices; Electric contacts; Electric fields; Elementary excitations; Energy; Exchange; Formations; letter; Magnetic fields; Mathematical and Computational Physics; Molecular; Momentum; Nanowires; Optical and Plasma Physics; Particle spin; Physics; Quantum computing; Scanning electron microscopy; Sciences of the Universe; Semiconductor devices; Signatures; Spin-orbit interactions; Theoretical; Topology; Transport; Germany; Condensed Matter - Mesoscale and Nanoscale Physics
• ISSN: 1745-2473; 1745-2481
• DOI: 10.1038/nphys4070

Signatures of spin–momentum-locked gap states in nanowire quantum point contacts that have all-electrical origin could provide the conditions for the quasiparticle excitations required for topological quantum computing. Spin–momentum locking in a semiconductor device with strong spin–orbit coupling (SOC) is thought to be an important prerequisite for the formation of Majorana bound states 1 , 2 , 3 . Such a helical state is predicted in one-dimensional (1D) nanowires subject to strong Rashba SOC and spin-mixing 4 —its hallmark being a characteristic re-entrant behaviour in the conductance. Here, we report direct experimental observations of the re-entrant conductance feature, which reveals the formation of a helical liquid, in the lowest 1D subband of an InAs nanowire. Surprisingly, the feature is very prominent also in the absence of magnetic fields. This behaviour suggests that exchange interactions have a substantial impact on transport in our device. We attribute the opening of the pseudogap to spin-flipping two-particle backscattering 5 , 6 , 7 . The all-electric origin of the ideal helical transport could have important implications for topological quantum computing.