Determine whether observed features correspond to an actual sweet spot

Determine whether the measurement in Device A at hybrid plunger gate voltage ABS = 62 mV, which exhibits both signs of non-local conductance (RL) and a cross in the correlated local conductance (LL · RR), corresponds to an actual sweet spot in the minimal Kitaev chain characterized by equality of elastic co-tunneling and crossed Andreev reflection rates (t = Δ), given indications of strong quantum dot–Andreev bound state interaction and potential low Majorana polarization affecting interpretation.

Background

In the minimal Kitaev chain realized with two quantum dots coupled via a semiconductor–superconductor hybrid segment, a sweet spot is defined by the equality of elastic co-tunneling (t) and crossed Andreev reflection (Δ), at which emergent Majorana zero modes are expected. Charge stability diagrams (LL * RR) and non-local conductance (RL) are used to identify this condition experimentally.

At ABS = 62 mV in Device A, the authors observe both signs of non-local conductance and a cross in the correlated conductance—features typically associated with a sweet spot. However, they note that the non-local features depend mostly on the left-dot gate (LM), suggesting strong quantum dot–Andreev bound state interaction, and explicitly state uncertainty about whether this configuration constitutes an actual sweet spot, possibly due to low Majorana polarization.