Robustness to gate imperfections of the tunneling enhancement effect in double quantum dots

The conductance of a tunnel barrier can exhibit a very large enhancement, as a result of constructive interference, if two constrictions are symmetrically placed around the barrier itself, thus defining a cavity. This phenomenon could be exploited for a sensitive detector of electric or magnetic fields, due to the strong dependence of the enhancement effect on symmetry. In order to assess the feasibility of such a sensor, we have studied the robustness of its operation with respect to fabrication tolerances in the lithographic process for the depletion gates used for the definition of the cavity. Here we report results that appear encouraging, since the enhancement effect seems to survive in the presence of localized deformations of the confining depletion gates, while deviations on a larger scale can be compensated modifying the applied gate potentials.