Low temperature conductance fluctuations in double-dot system

We have studied the low temperature conductance fluctuations in double-dot systems. The electron wave coupling between ballistic quantum dots has been investigated in a pair of coupled quantum dots defined by several independently-tunable quantum-point-contacts (QPCs). Reproducible conductance fluctuations are observed in the low temperature magneto-conductance at low magnetic fields and a clear difference between weak and strong couplings has been identified as the gap of the QPC corresponding to the inter-dot coupling is varied. This suggests clear evidence for a specific spread of the coupling orbit over the whole dot region.