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.  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.
 

Dr. Hao Zhang received his B.S. in Physics from Peking University in 2010. He obtained his PhD in Physics (Albert Chang group) from Duke University in 2014, working on electron correlation effect in quantum point contacts.  He started working as a postdoc in Leo Kouwenhoven group at Delft University of Technology since 2014.  His current research focuses on Majorana zero modes in hybrid superconductor-semiconductor nanowire systems.