Van der Waals semiconductors as Josephson junction barriers for superconducting qubits

Two-dimensional van der Waals (vdW) materials are promising platforms for superconducting quantum devices due to their single-crystallinity, low defect density, and lack of dangling bonds. vdW semiconductors—whose band gaps are typically ~5x smaller than in vdW insulators like hBN—can exhibit tunneling through ~10 layers, enabling large-area, homogeneous Josephson junctions with greater participation ratios in ultra-clean vdW interfaces. We characterize the dc and microwave electronic properties of vdW Josephson junctions with ultra-high-purity WSe₂ semiconductor barriers and discuss their potential as components for small-footprint, high-quality-factor superconducting qubits.