Extended Data Fig. 4: Wide graphene Josephson junction.

a–d, Top panels show differential resistance maps as a function of back-gate voltage and dc current bias of sample HV88-G (W = 2.3 μm, L = 107 nm). Bottom panels are linecuts of the differential resistance at dc current biases of 0 nA and 26 nA, which show the emergence of supercurrent pockets (zero resistance reached by the blue curve), and the corresponding resistive state (yellow curve). The magnetic field is indicated in each top panel. Supercurrent is visible only when the resistance is not quantized, that is, at filling factors of QH plateaus that are not developed, or in between plateaus. When a QH plateau emerges, as for instance the h/2e² plateau for B ≥ 4 T or the h/6e² plateau for B ≥ 6 T, the supercurrent vanishes. This weakness is even more marked in sample HV88-H shown in SI, which is twice longer. Note that the oscillatory behavior of the resistance (see red curve at 26 nA) is characteristic of QH devices in two-terminal configuration with L ≪ W, see ref. ³⁷.