Fig. 4: Current in the bistable regime vs conductance.

Time-averaged tunneling current 〈I〉_bistable just before the loss of the bistable regime as a function of the conductance G normalized to the conductance quantum G₀, for STM Josephson junctions made with tip and sample of Pb. The colored circles correspond to the experimental results whereas the line corresponds to the expression \({I}_{{{\rm{c}}}}\frac{\Delta \tau }{4{\tau }_{{{\rm{D}}}}}\). I_c is determined as a function of G following ref. ²¹. In the upper left inset we show the time-averaged tunneling current \(\langle I \rangle\) vs the time-averaged voltage \(\langle V \rangle\). Each line corresponds to a different tunneling conductance, following the color code of the circles in the main panel (G = 0.61G₀ (violet), 0.50G₀ (blue), 0.43G₀ (light blue), 0.37G₀ (cyan), 0.31G₀ (light cyan), 0.27G₀ (green), 0.22G₀ (light green), and 0.18G₀ (yellow)). Dashed lines in the inset are for decreasing bias. In the lower right inset we show a map of the amplitude of the oscillatory signal in the bistable regime showing atomic resolution in 2H-NbSe₂. The amplitude of the oscillatory signal improves significantly the signal to noise ratio and increases with I_c. White scale bar is 1 nm long. In the upper left corner of the inset we show the Fourier transform, where we can identify the Bragg peaks of the hexagonal Se lattice (white circles) and the Bragg peaks due to the PDW (red circles, more details in Supplementary Fig. 6 and in the Supplementary Information Section 4).