Dependence of topological signatures to junction geometry in planar Josephson junctions

Planar Josephson junction based on two-dimensional electron gas (2DEG) is a promising platform for the study of topological superconductivity and Majorana zero modes. Here we fabricate planar Josephson junctions using epitaxial aluminum on semiconducting indium arsenide quantum wells. By adding two tunneling probes at the ends of the junction, we are capable of studying both supercurrent crossing the junction and tunneling spectroscopy at the ends of the junction. The supercurrent in our junctions is known to have a non-monotonic behavior with a proper in-plane magnetic field [1]. We further explore the supercurrent non-monotonic behavior in junctions with various geometries (superconducting lead width, length and width of the junction). For the tunneling spectroscopy, we first optimize the quantum point contact (QPC) by testing different dielectrics and gate configurations. With the optimized QPC, we systematically study the low-energy states probed at the ends of the junction that could be used to study end-to-end correlated states.

[1] M. Dartiailh, et. al, PRL 126, 036802 (2021).