Tailoring supercurrent confinement in tunable superconducting weak links

在这个项目中，我们将研究电流限制在扩展的二维超导弱链接定制可调静电收缩双层石墨烯。通过这种弱链接的超电流将被测量为一系列限制架构的磁场的函数。通过测量临界电流的场依赖性，夫琅和费图案，我们将确定弱连接几何形状和磁场依赖性之间的相关性。这种方法将使我们能够开发一个模型，以确定在非均匀的弱连接，这仍然是一个悬而未决的问题，至今的超导分布。在双层石墨烯中静电打开带隙的可能性将使我们有机会探索可调和静电可成形的纳米级弱连接，我们将基于低欧姆边缘连接的hBN-双层石墨烯-hBN vdW异质结构来制造。在异质结构的顶部上使用附加的电介质层允许任何种类的顶部栅控纳米结构的高度灵活的设计，而不会降低迁移率和接触电阻。除了探索电荷载流子的一维限制外，我们还将实现更复杂的双层石墨烯系统，如最近理论上提出的电子干涉仪。

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.