Graphene Josephson junctions in the quantum Hall regime

The combination of superconductivity and quantum Hall effect is fundamentally interesting, which may decode the scattering mechanism between 1D edge channels and the superconductors, and shed light on the search of new Majorana zero modes. The main challenge is technical: sufficiently high mobility allowing quantum Hall effect resolved at a low field, and ohmic contacts that allows induction of superconducting proximity effect. Both challenges can be overcome in graphene-based devices. Furthermore, graphene hosts additional novel quantum Hall phases due to symmetry break or strong electron-electron interactions, which makes it to be unique compared with other candidates. Utilizing NbN as the contact selection to graphene channels, our initial results suggest successful proximity in its Josephson junction forms. Detailed studies further tuning the junctions as well as of other superconducting structures are ongoing, and will be discussed in this talk.