Fig. 3 | Communications Physics

Fig. 3

From: Spectroscopy of the superconducting proximity effect in nanowires using integrated quantum dots

Fig. 3

Proximity gap in the resonant tunneling regime. ad Experiment (i), resonant tunneling model (ii), and cross-sections of both (iii) for different Coulomb blockade (CB) resonances. The color bar is the differential conductance G (e2/h) as a function of the backgate voltage VBG and the source-drain bias voltage VSD. Light green and orange lines indicate the VBG of the cross-sections in (iii). e Relative positions of the electrochemical potentials of the normal contact (μN), the superconductor (μS = μN −  eVSD) and the quantum dot (μQD) for selected points (I, II, III) in the charge stability diagram. The tips of the diamonds are shifted in gate voltage by ΔVBG = 2Δ*/(βe) with β the lever arm of VBG. In a, the tunnel coupling is almost a factor of 3 larger than in bd. From the model, the tunnel coupling Γ is essentially constant for bd, whereas the value for the induced superconducting energy gap varies from Δ* = 165 μeV in a, Δ* = 145 μeV in b, Δ* = 85 μeV in c, to Δ* < 10 μeV in d

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