Universal transport properties of three-dimensional topological insulator nanowires

We report theoretical calculations of electronic and transport properties mediated by topological helical states on the walls of three-dimensional topological insulator (TI) nanowires. A universal regime of quantized conductance and fluctuations is found that is induced by disorder. The average conductance of the disordered nanowire scales as a function of the number of transmission channels N in a universal form = independent of the system details. For instance, for Bi2Se3 nanowires cleaved along the x or y direction with the quintuple layers along the z direction =(5/12)N+1/2. The universal and quantized behavior is due to the topological physics happening on the walls of the nanowire under the influence of disorder.