A novel quantum interference probe of the energy spectrum of coupled nanodevices

Quantum transport of an array of quantum billiards is investigated as a function of the coupling strength of the quantum point contacts that connect the individual billiards. A fractal analysis of the measured magneto-conductance fluctuations is used as a novel non-invasive probe of two characteristic energy scales of the energy level spectrum—the average energy level spacing and average energy level broadening. This analysis reveals a marked transition in the coherent area of the array as the coupling between the billiards is increased and the array evolves into a combined quantum system.