One-dimensional proximity superconductivity in the quantum Hall regime

Extensive efforts have been undertaken to combine superconductivity and the quantum Hall effect so that Cooper-pair transport between superconducting electrodes in Josephson junctions is mediated by quantized edge states. This interest is currently motivated mainly by the prospect of creating topologically-protected quasiparticles but also extends into metrology and device applications. So far, it has proven challenging to achieve detectable supercurrents through quantum Hall conductors. Here we show that domain walls in minimally twisted bilayer graphene support robust proximity superconductivity in quantizing fields, allowing junctions with steady (non-oscillatory) critical currents over a several Tesla range approaching the upper critical field. The supercurrent is limited only by the quantum conductance of ballistic 1D channels residing inside the walls. Our findings offer an interesting avenue for exploring both fundamental physics and device applications.