Tuning Nonlinear Charge Transport between Integer and Fractional Quantum Hall States

Abstract

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 nu=1 and nu*<or=1 in which both the fractional filling nu* and the coupling strength can be finely and independently tuned. A peculiar crossover from insulating to conducting behavior as nu* 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.

Imaging Fractional Incompressible Stripes in Integer Quantum Hall Systems

“…The presence of fractional IS also explains the observation of Luttinger liquid behavior in tunneling experiments between ν = 1 phases (Fermi liquids), presented in Ref. [9]. Such results were interpreted by assuming that electrons tunnel through a region with local fractional filling factor ν * separating the two main incompressible phases at ν = 1.…”

“…Despite a number of experimental and theoretical studies, the issue of fractional order within integer QH systems is still an open question. A number of experiments showed clear indications of fractional phases in constrictions, either in terms of fractional quantization of conductance [2,3] or Luttinger-like non-linear features [6][7][8][9], although even the simple problem of how an ideal integer edge can "branch" and give rise to fractional edges remains unclear. On the other hand, recent interferometry experiments [10] and out-of-equilibrium energy spectroscopy data [11] indicate that an integer edge can behave as a monolithic object and shows no clear evidence of an inner structure.…”

Selective control of edge-channel trajectories by scanning gate microscopy

“…The fundamental idea behind our experiments consists in exploiting the QPC not only to control the distance between counterpropagating edges (as in tunneling experiments [6,7]) but also to set the number of edges flowing around each of the two split gates. An essential role here is played by the SGM tip, which is exploited first to determine the filling factor underneath the two split gates and then to put the selected edge states in interaction.…”

“…In order to address these issues we are exploring the use of scanning gate microscopy (SGM) to control the trajectory and interaction of edge channels based on our previous results on quantum point contact (QPC) devices in the QH regime [4,5,6,7]. In the present work, the two split gates of the QPC play a double role: they not only allow us to bring the edges in close proximity, but they also provide the ability to select the edges that are sent to the center of the QPC.…”

Observation of Coulomb blockade and ballistic tunneling in graphene single electron transistor

“…At high magnetic field, in the quantum Hall regime, we observed ballistic tunneling of the carriers through the graphene SET, contrary to the Coulomb blockades observed while approaching the vicinity of the Dirac point. graphene, single electron transistor, Coulomb blockade, tunneling, quantum Hall state PACS number(s): 72.80Vp, 73.23.Hk, 73.43.-f Citation: Tan Z B, Liu G T, Lu L, et al Observation of Coulomb blockade and ballistic tunneling in graphene single electron transistor.Quantum point contacts, single electron transistors and quantum dots have been widely studied in the past decades [1][2][3][4][5][6][7][8]. They are widely used as tools to determine the integer and fractional charges in the quantum Hall regime [3,4], and to study the electron interference behavior of the edge states [5,6] and the tunneling/scattering between edge channels near the constrictions [7,8].…”