Tuning Nonlinear Charge Transport between Integer and Fractional Quantum Hall States

Controllable point junctions between different quantum Hall phases are a necessary building block for the development of mesoscopic circuits based on fractionally charged quasiparticles. We demonstrate how particle-hole duality can be exploited to realize such point-contact junctions. We show an implementation for the case of two quantum Hall liquids at filling factors ν=1 and ν^*≤1 in which both the fractional filling ν^* and the coupling strength can be finely and independently tuned. A peculiar crossover from insulating to conducting behavior as ν^* goes from 1/3 to 1 is observed. These results highlight the key role played on interedge tunneling by local charge depletion at the point contact.