Another exciting possibility is realizing a spin-helical liquid in InSb nanowires. In a spin-helical liquid, the spin orientation becomes coupled to the electron propagation direction when a magnetic field is applied perpendicular to th espin-orbital field (e.g. along the nanowire). We are interested in the intriguing possibility of using InSb nanowires coupled with nanoscale ferromagnets to detect such spin-helical modes and use them as spin filters or to couple single spins from separate quantum dots. Spin-helical liquids are also one of the key ingredients for realizing Majorana zero-modes in nanowires proximitized with a superconductor.
A major hurdle for the experimental realization of exotic physics such as spin-helical states and Majorana zero modes in 1D InSb semiconducting nanowires is the disorder introduced to the system during standard nanofabrication processes. The effect of this disorder is further compounded by charge-trapping defects in the conventional amorphous oxides used as gate dielectrics in these devices. Two-dimensional van der Waals materials, such as graphite, offer a novel solution as they are atomically flat, single-crystalline, and largely defect-free. Preliminary work as shown that the use of hexagonal boron nitride, a 2D insulator, in place of thermal oxides can considerably improve the quality of nanowire devices [3,4]. We are exploring the exciting opportunities to create nanowire devices which fully incorporate 2D materials for the gates, dielectrics, and encapsulation layers, creating systems with both optimally low material disorder and intrinsic protection from fabrication-induced disorder. These devices should serve as the best-case platform for studying quantum transport phenomena in semiconducting nanowires.
