Tuning non-linear 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 filling factors $\nu =1$ and ${\nu }^{\ast }\le 1$ in which both the fractional filling ${\nu }^{\ast }$ and the coupling strength can be finely and independently tuned. A peculiar crossover from insulating to conducting behavior as ${\nu }^{\ast }$ goes from 1/3 to 1 is observed. These results highlight the key role played on inter-edge tunneling by local charge depletion at the point contact.