Majorana zero-modes hold great promise for topological quantum computing. Tunnelling spectroscopy in electrical transport is the primary tool to identify the presence of Majorana zero-modes, for instance as a zero-bias peak (ZBP) in differential-conductance. The Majorana ZBP-height is predicted to be quantized at the universal conductance value of 2e2/h at zero temperature. Interestingly, this quantization is a direct consequence of the famous Majorana symmetry, 'particle equals antiparticle'. The Majorana symmetry protects the quantization against disorder, interactions, and variations in the tunnel coupling. Previous experiments, however, have shown ZBPs much smaller than 2e2/h, with a recent observation of a peak-height close to 2e2/h. Here, we report a quantized conductance plateau at 2e2/h in the zero-bias conductance measured in InSb semiconductor nanowires covered with an Al superconducting shell. Our ZBP-height remains constant despite changing parameters such as the magnetic field and tunnel coupling, i.e. a quantized conductance plateau. We distinguish this quantized Majorana peak from possible non-Majorana origins, by investigating its robustness on electric and magnetic fields as well as its temperature dependence. The observation of a quantized conductance plateau strongly supports the existence of non-Abelian Majorana zero-modes in the system, consequently paving the way for future braiding experiments.
@article{arxiv.1710.10701,
title = {Quantized Majorana conductance},
author = {Hao Zhang and Chun-Xiao Liu and Sasa Gazibegovic and Di Xu and John A. Logan and Guanzhong Wang and Nick van Loo and Jouri D. S. Bommer and Michiel W. A. de Moor and Diana Car and Roy L. M. Op het Veld and Petrus J. van Veldhoven and Sebastian Koelling and Marcel A. Verheijen and Mihir Pendharkar and Daniel J. Pennachio and Borzoyeh Shojaei and Joon Sue Lee and Chris J. Palmstrom and Erik P. A. M. Bakkers and S. Das Sarma and Leo P. Kouwenhoven},
journal= {arXiv preprint arXiv:1710.10701},
year = {2018}
}