  We investigate theoretically a Fano interferometer composed by STM and AFM
tips close to a Kitaev dimer of superconducting adatoms, in which the adatom
placed under the AFM tip, encloses a pair of Majorana fermions (MFs). For the
binding energy $\Delta$ of the Cooper pair delocalized into the adatoms under
the tips coincident with the tunneling amplitude $t$ between them, namely
$\Delta$ = $t$, we find that only one MF beneath the AFM tip hybridizes with
the adatom coupled to the STM tips. As a result, a gate invariance feature
emerges: the Fano profile of the transmittance rises as an invariant quantity
depending upon the STM tips Fermi energy, due to the symmetric swap in the gate
potential of the AFM tip.
