Publications Details

Designing Nanomagnet Arrays for Topological Nanowires in Silicon

Maurer, Leon M.; Gamble, J.K.; Tracy, Lisa A.; Eley, S.; Lu, Tzu-Ming L.

Recent interest in topological quantum computing has driven research into topological nanowires, one-dimensional quantum wires that support topological modes, including Majorana fermions. Most topological nanowire designs rely on materials with strong spin-orbit coupling, such as InAs or InSb, used in combination with superconductors. It would be advantageous to fabricate topological nanowires with Si owing to its mature technology. However, the intrinsic spin-orbit coupling in Si is weak. One approach that could circumvent this material deficiency is to rotate the electron spins with nanomagnets. Here we perform detailed simulations of realistic Si/SiGe systems with an artificial spin-orbit gap induced by a nanomagnet array. Most of our results are generalizable to other nanomagnet-based topological nanowire designs. By studying several concrete examples, we gain insight into the effects of nanomagnet arrays, leading to design rules and guidelines. In particular, we develop a recipe for eliminating unwanted gaps that result from realistic nanomagnet designs. Finally, we present an experimentally realizable design using magnets with a single polarization.