Van der Waals Josephson Junctions for 2D Superconducting Qubits

State-of-the-art superconducting qubits currently face numerous materials-limited roadblocks to increasing coherence times for fault-tolerant computing while shrinking form factors for scalability. Two-dimensional van der Waals (vdW) materials offer an ideal platform to circumvent these issues owing to their single-crystallinity, low defect density, and lack of dangling bonds. In particular, the vdW semiconductor WSe₂—whose band gap is ~5x smaller than that of vdW insulator hBN—can exhibit tunneling through ~10 layers, enabling Josephson junctions with exceptional tunnel barrier homogeneity and lower loss compared to deposition-grown junctions by confining fields in ultra-clean vdW interfaces while achieving 100x smaller qubit area. We characterize the electronic properties of vdW Josephson junctions with ultra-high-purity WSe₂ barriers and discuss their potential in small-footprint, long-coherence-time superconducting qubits.