Superconducting Edge Contact and Quantum Interference Between Two-Dimensional van der Waals and Three-Dimensional Conventional Superconductors

Two-dimensional (2D) transition-metal dichalcogenide (TMD) superconductors have unique and desirable properties for integration with conventional superconducting circuits. These include the ability to form atomically-flat and clean interfaces with stable tunnel barriers, increased kinetic inductance due to the atomically-thin geometry, and resilience to very high in-plane magnetic fields. However, integration of 2D TMD superconductors in conventional superconducting circuits, particularly those employing microwave drive and readout of qubits, requires that a fully superconducting contact be made between the 2D material and a three-dimensional (3D) superconductor. Here, we present an edge contact method for creating zero-resistance contacts between 2D \nbse and 3D aluminum. These hybrid Al-NbSe_2 Josephson junctions (JJs) display a Fraunhofer response to magnetic field with micron2-scale effective areas as the thin NbSe_2 allows field to uniformly penetrate the flake. We present a model for the supercurrent flow in a 2D-3D superconducting structure by numerical solution of the Ginzburg-Landau equations and find good agreement with experiment. The devices formed from 2D TMD superconductors are strongly influenced by the geometry of the flakes themselves as well as the placement of the contacts to bulk 3D superconducting leads. These results demonstrate our ability to graft 2D TMD superconductors and nano-devices onto conventional 3D superconducting materials, opening the way to a new generation of hybrid superconducting quantum circuits.