Effect of imperfections on the tunneling enhancement phenomenon in symmetric double quantum dots

The conductance of a pair of quantum dots, coupled through a tunnel barrier and connected to two external leads, exceeds the conductance of the tunnel barrier alone (tunneling enhancement effect) if the device is symmetrical, while it strongly decreases if the symmetry is destroyed. This device could then be used to implement a sensitive detector of symmetry breaking quantities, such as magnetic fields. We present a numerical study of the robustness of this phenomenon to the presence of imperfections. We find that, while a realistic amount of edge roughness in the depletion gates defining the structure does not compromise the enhancement effect significantly, and also lithographic errors can be compensated by properly tuning the voltages applied to the gates, the presence of randomly located ionized dopants in the heterostructure can strongly degrade the conductance enhancement and thus particular care has to be taken in terms of cleanliness and mobility of the heterostructure