Disorder Suppression in Topological Semiconductor-Superconductor Junctions

Understand

Disorder in a proximitizing bulk superconductor can scatter quasiparticles in a putative topological superconductor and eventually destroy the topological superconducting state.

• We use a scattering approach and a random-matrix calculation to estimate the disorder scattering time in a topological Josephson junction.
• We find that the disorder scattering rate from the bulk of the superconductor, even in the strong coupling limit, is suppressed in the ratio of Fermi momenta between the semiconductor and superconductor.
• This suppression of disorder scattering is accompanied by near perfect Andreev reflection at such semiconductor/superconductor interfaces, which can be used as a signature of such clean proximity effect.