Quantum Hall based Aharonov-Bohm spectroscopy

Aharonov-Bohm spectroscopy is a powerful tool to study the quantum statistics of quasi particles in the integer and fractional quantum Hall regimes. Related major activities are in particular driven by the search for non-abelian states which could pave the path towards topological quantum information processing. However, a detailed understanding of how interaction affects the quantum states is still lacking for both quantum Hall effects. We will tackle this challenge by performing phase dependent magneto-transport experiments in conjunction with self consistent model calculations taking into account electron-electron interaction.

In this project, titled Quantum Hall based Aharonov-Bohm spectroscopy: electron-electron interaction in non-linear magnetotransport, our focus is the nonlinear but still phase-coherent regime of edge channel transport; this goes beyond existing efforts. The experiments will be conducted on an Aharonov-Bohm interferometer, which can be employed as a quantum switch, defined in a two-dimensional electron puddle in a GaAs based heterostructure. Phase coherent quantum Hall edge states serve as the interferometer arms. The geometry of the puddle and nature of these edge states are controlled by voltages applied to top gates. This field effect technique allows us to tune the steepness of the confinement potential and, thus, define asymmetric edges guiding individual interferometer arms. 

Our previous studies demonstrate a strong impact of such gate-defined asymmetries on the quantum Hall states. We plan to study phase coherent transport properties of the quantum switch in the nonlinear regime as a function of symmetry and other parameters including magnetic field strength, temperature, carrier density and mobility. Our studies will provide a new level of understanding of how interactions affect the quantum Hall states.