Critical current fluctuations in graphene Josephson junctions

We have studied 1/f noise in critical current [Formula: see text] in h-BN encapsulated monolayer graphene contacted by NbTiN electrodes. The sample is close to diffusive limit and the switching supercurrent with hysteresis at Dirac point amounts to [Formula: see text] nA. The low frequency noise in the superconducting state is measured by tracking the variation in magnitude and phase of a reflection carrier signal [Formula: see text] at 600–650 MHz. We find 1/f critical current fluctuations on the order of [Formula: see text] per unit band at 1 Hz. The noise power spectrum of critical current fluctuations [Formula: see text] measured near the Dirac point at large, sub-critical rf-carrier amplitudes obeys the law [Formula: see text] where [Formula: see text] and [Formula: see text] at [Formula: see text] Hz. Our results point towards significant fluctuations in [Formula: see text] originating from variation of the proximity induced gap in the graphene junction.