Extended Data Fig. 4: Quantum point contact characterization and stability of the zero-bias peak. | Nature

Extended Data Fig. 4: Quantum point contact characterization and stability of the zero-bias peak.

From: Evidence of topological superconductivity in planar Josephson junctions

Extended Data Fig. 4

a, G as a function of Vsd and QPC voltage Vqpc at zero field in device 1. b, Differential conductance at zero source–drain bias, G(Vsd = 0 mV), versus averaged differential conductance at finite source–drain bias, G(|Vsd| > 0.4 mV). The green line is the theoretically predicted conductance in an Andreev-enhanced QPC, \({G}_{{\rm{S}}}=2{G}_{0}\frac{{G}_{{\rm{N}}}^{2}}{{\left(2{G}_{0}-{G}_{{\rm{N}}}\right)}^{2}}\) (ref. 38), where \({G}_{{\rm{S}}}\) is the sub-gap conductance, \({G}_{{\rm{N}}}\) is the above-gap conductance and \({G}_{0}=2{e}^{2}/h\) is the quantum of conductance. No fitting parameters have been used. c, G as a function of Vsd and Vqpc at parallel field B|| = 780 mT and \(\phi \) ≈ 0.8π for gate voltages V1 = −110 mV and Vtop = −35 mV. d, G as a function of Vsd and Vtop at B|| = 600 mT and \(\phi \) ≈ 0 for V1 = −118.5 mV and Vqpc = −2.366 mV. In both c and d, the ZBP is robust against variation of the above-gap conductance of about one order of magnitude. ef, G as a function of Vsd and B||, for different values of \(\phi \) in device 1. The plots have been reconstructed from measurements similar to those shown in Fig. 2 of the main text. For \(\phi \) ≈ π, a ZBP forms at B|| = 0.35 T, whereas for \(\phi \) = 0 it appears at B|| = 575 mT. The ZBP at \(\phi \) ≈ π oscillates and moves away from zero energy as the field is increased.

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