Induced superconductivity in InSb 2DEGs

Superconductor-semiconductor hybrid systems are promising candidates to create Majorana zero modes (MZMs). Using a semiconductor two-dimensional electron gas (2DEG) could allow one to create complex networks required for Majorana qubit schemes. In this regard, InSb 2DEGs stand out due to their large g-factor, strong spin-orbit coupling, and low disorder. We integrate such high-quality 2DEGs with NbTiN to create Josephson junctions (JJs), thus providing the first demonstration of induced superconductivity in InSb 2DEGs. Remarkably, the supercurrent persists over several microns and shows distinct signatures of ballistic transport. Applying an in-plane magnetic field produces a revival of the supercurrent due to a Zeeman induced 0-π transition, where the transition field scales linearly with the junction length. Moreover, we show that this transition can be tuned in-situ using gate voltages, which allows us to map out the free energy landscape of the JJ as a function of density and magnetic field. Our experiments are consistent with the expected behavior of 0-π transitions in ballistic JJs and are an important step toward creating robust MZMs in 2DEG-based π-junctions.