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temperature; for chosen t/D = 0 . 001 , we indeed find that for T/D = 10 − 5 ≈ 0 . 1 T 0 $_{K}$, the conductance form takes the form of a nearly symmetric anti-resonance, in agreement with the experiment. The minimum of the anti-resonance is located at lower value of E = ϵ a / Γ a as compared to the non-interacting case (where it is found exactly at E = 0 ), since the physi- cal mechanism for its occurrence is completely different: in the non-interacting case we observe a complete suppression of the conductance due to quantum interference between dif- ferent conductance pathways, while in the interacting case the incomplete suppression results from the separation of the en- ergy scales T 0 K and T 2 K with the experimental temperature set on an intermediate scale so that T 2 K < T < T 0 $_{K}$. The shift from E = 0 is not observable experimentally, since the exact value of the parameter ϵ a is not known: it has to be inferred indirectly from known gate voltages on the electrodes and the capacitances. 

If the inter-dot tunneling t is increased so that the exchange coupling becomes comparable or exceeds the Kondo temper- ature, the conductance curves no longer exhibit a Fano-like antiresonance, not even at elevated temperatures, see Fig. 11. Instead, as E is reduced so that the side-coupled dot becomes occupied by one electron, the two electrons (one from each quantum dot) bind to a local singlet on the temperature scale of J ∼ 4 t $^{2}$/U and there are no other lower temperature scales. 

The interpretation of the anti-resonance in terms of a ther- 

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mally suppressed second-stage Kondo screening is supported by the experimental results for the temperature-dependence of the resonant conductance (Fig. 2c in Ref. 34) which indicate a logarithmic behavior. This temperature variation corresponds to the high-temperature range in Fig. 10b). The experimen- tal results do not indicate any saturation of G for the lowest experimentally accessible temperatures, however this might simply indicate that the temperature is not sufficiently bel ow T K , or that t is indeed very small and thus T 2 K is exponentially low. Further confirmation for the interpretation in terms of the two-stage Kondo effect could be obtained by also consid- 

