Transport study of an ultra-low density dual quantum dot

We report on transport results of an ultra-low density dual quantum dot. We observe that the conductance measured across one low density quantum dot is affected dramatically by the existence of the other low density quantum dot in close proximity. We have found turn on/off characteristics and a hysteresis in the conductance through one quantum dot when the other quantum dot is switched on by the gate bias. All these features are reproducible and have strong temperature dependences. Our observation probes a new low density regime of coupled zero dimensional systems and we interpret our data as due to an exchange interaction driven instability similar to what was observed in a coupled two dimensional system.