Tailoring supercurrent confinement in tunable superconducting weak links

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In this project we will study electrical current confinement in extended 2D superconducting weak links by tailoring tunable electrostatic constrictions in bilayer graphene. The supercurrent through such weak links will be measured as a function of the magnetic field for a range of confinement architectures. By measuring the field dependence of the critical current, the Fraunhofer pattern, we will determine the correlation between weak link geometry and the magnetic field dependence. This approach will allow us to develop a model to determine the supercurrent distribution in inhomogeneous weak links, which remains an unresolved problem so far. The possibility to electrostatically open a band gap in bilayer graphene will give us the opportunity to explore a tunable and electrostatically shapeable nanoscale weak link, which we will fabricate based on low-ohmic edge connected hBN-bilayer graphene-hBN vdW heterostructures. The usage of an additional dielectric layer on top of a heterostructure allows the highly flexible design of any kind of top gated nanostructures without degrading mobility and contact resistance. Besides exploring the one-dimensional confinement of charge carriers we will also realize more complex systems in bilayer graphene like electronic interferometers as have recently been theoretically proposed.