Quantized Majorana conductance (Publication with Expression of Concern. See vol. 581, 2020)

Majorana zero-modes-a type of localized quasiparticle-hold great promise for topological quantum computing(1). Tunnelling spectroscopy in electrical transport is the primary tool for identifying the presence of Majorana zero-modes, for instance as a zero-bias peak in differential conductance(2). The height of the Majorana zero-bias peak is predicted to be quantized at the universal conductance value of 2e(2)/h at zero temperature(3) (where e is the charge of an electron and h is the Planck constant), as a direct consequence of the famous Majorana symmetry in which a particle is its own antiparticle. The Majorana symmetry protects the quantization against disorder, interactions and variations in the tunnel coupling(3-5). Previous experiments(6), however, have mostly shown zero-bias peaks much smaller than 2e(2)/h, with a recent observation(7) of a peak height close to 2e(2)/h. Here we report a quantized conductance plateau at 2e(2)/h in the zero-bias conductance measured in indium antimonide semiconductor nanowires covered with an aluminium superconducting shell. The height of our zero-bias peak remains constant despite changing parameters such as the magnetic field and tunnel coupling, indicating that it is a quantized conductance plateau. We distinguish this quantized Majorana peak from possible non-Majorana origins by investigating its robustness to electric and magnetic fields as well as its temperature dependence. The observation of a quantized conductance plateau strongly supports the existence of Majorana zero-modes in the system, consequently paving the way for future braiding experiments that could lead to topological quantum computing.