  The Josephson effect is one of the most studied macroscopic quantum phenomena
in condensed matter physics and has been an essential part of the quantum
technologies development over the last decades. It is already used in many
applications such as magnetometry, metrology, quantum computing, detectors or
electronic refrigeration. However, developing devices in which the induced
superconductivity can be monitored, both spatially and in its magnitude,
remains a serious challenge. In this work, we have used local gates to control
confinement, amplitude and density profile of the supercurrent induced in
one-dimensional nanoscale constrictions, defined in bilayer graphene-hexagonal
boron nitride van der Waals heterostructures. The combination of resistance
gate maps, out-of-equilibrium transport, magnetic interferometry measurements,
analytical and numerical modelling enables us to explore highly tunable
superconducting weak links. Our study opens the path way to design more complex
superconducting circuits based on this principle such as electronic
interferometers or transition-edge sensors.
