Tunneling signature of superconducting coupling in graphene quantum Hall edge states

Recent development in graphene device fabrication has allowed the observation of quantum Hall (QH) edge states at very low magnetic fields. By employing graphite back gate, we can produce broken symmetry QH states in graphene in a low magnetic field, while still preserving the superconductivity of a type-II superconductor NbN. The induced superconducting coupling of counter-propagating QH edge states spaced within the coherence length of NbN can be probed by quasiparticle tunneling. To measure the tunneling spectra, we build a local top gate to bring the normal QH edge state to proximity of the proximitized QH edge state. In addition, we will also present Josephson junction based on a pair of proximitized counter propagating QH edge states.