  We study the low-energy transport properties of a hybrid device composed by a
native quantum dot coupled to both ends of a topological superconducting
nanowire section hosting Majorana zero-modes. The account of the coupling
between the dot and the farthest Majorana zero-mode allows to introduce the
topological quality factor, characterizing the level of topological protection
in the system. We demonstrate that Coulomb interaction between the dot and the
topological superconducting section leads to the onset of the additional
overlap of the wavefunctions describing the Majorana zero-modes, leading to the
formation of trivial Andreev bound states even for spatially well-separated
Majoranas. This leads to the spoiling of the quality factor and introduces a
constraint for the braiding process required to perform topological quantum
computing operations.
