Quantized Andreev conductance in semiconductor nanowires

One-dimensional electron systems can exhibit quantized conductance. The plateau conductance doubles if the transport is dominated by Andreev reflection. Here, we report quantized conductance observed in both Andreev and normal-state transport in PbTe-Pb and PbTe-In hybrid nanowires. The Andreev plateau is observed at 4e²/h, twice the normal plateau value of 2e²/h. In comparison, Andreev conductance in the best-optimized III-V nanowires is nonquantized due to mode-mixing-induced dips (a disorder effect), despite the quantization of normal-state transport. The negligible mode mixing in PbTe hybrids indicates an unprecedented low-disorder transport regime for nanowire devices, beneficial for Majorana research.