DARPA Topologically Protected Quantum Information Processing In Spin- Orbit Compled Semiconductors.

摘要

We proposed and studied in detail the non-Abelian topological order and Majorana fermions (MFs) in a heterostructure consisting of both electron- and hole-doped spin-orbit coupled semiconductors (e.g., InAs, InSb) and an s- wave superconductor (Nb, Al) in the presence of a suitably directed Zeeman field in both 2 and 1 dimensions. The experiments we proposed to reveal the MFs, zero bias conductance peak in local tunneling experiments and the fractional Josephson effect, have now been successfully carried out by a number of groups worldwide. We have analyzed the experimental results in detail, explaining the absence of the gap closing signatures before the emergence of the MFs in the electron doped nanowires, and deducing alternative scenarios for the emergence of the zero bias peaks so as to help rule out alternative interpretations of the experimental results. After an extensive set of analysis and publications, our current outlook is that although the positive experimental results are extremely encouraging, one cannot rule out the alternative interpretations for the experiments. This necessitated proposing a true smoking-gun signature of MFs in semiconductor nanowires which we also accomplished in terms of a charge tunneling interference experiment.