Extended Data Fig. 5: Fitting of conductance line-traces.

The measurements in Fig. 2 show a finite in-gap conductance in G_MM when ϕ_Δ = 0. Possible origins for this include thermal broadening, and small deviations in the QD plunger gate voltages from being precisely at μ_i = 0. Here we address the former, by comparing the conductance bias-traces with the theoretically expected shapes in the small lead-QD coupling limit (Γ ≪ k_BT) described in Methods. a. Repetitions of conductance spectra for G_LL and G_RR as a function of B_z, as shown in Fig. 2a. b. Line-cuts taken from the indicated position in (a), at B_z corresponding to ϕ_Δ = 0. G_LL is fitted to Eq. (18) and G_RR is fitted to Eq. (19), yielding estimates for t₁ and t₂. We find the conductances are well described by the temperature-limited fits and find both are described by the same broadening parameter (γ = 15.6). c. Repetition of conductance spectra for G_MM as a function of B_z from Fig. 2a. d. Using the t₁ and t₂ values extracted in (b), we fit the indicated G_MM line-cut from (c) to Eq. (20). In (i), γ is fixed to be the same value as extracted in (b), while in (ii) γ is included as fitting parameter. (iii) uses the same fitting as (ii), for a line-cut taken at a different 2π period as indicated in (c). The conductance is again well-described by the temperature-limited fit. A larger broadening parameter is however required, the origin of which is unclear and not captured by the numerical simulations. In (ii) and (iii) the measured conductance at V_M = 0 is ≈ 3 mG₀ larger than explained by the fits. From Eq. (16), this remainder would correspond to offsets in μ_L/μ_R on the order of ± 5 μeV. The plunger gate voltages are set with a resolution of 60 μV, which combined with a QD leverarm of ≈ 0.05 would translate to potential offsets on the order of 3 μeV in μ_L and μ_R. e-h. shows a repetition of the outlined procedure, for measurements using the charge configuration shown in Extended Data Fig. 11. A similar behaviour is observed.