Observation of a G = ½ e<sup>2</sup>/h quantized conductance plateau in a quantum point contact at the v = 2/3 fractional quantum Hall state

ORAL

Abstract

Quantum point contacts (QPCs) can be used to reflect quantum Hall edge states and probe the properties of fractional quasiparticles. We have investigated the v = 2/3 state in QPCs on a GaAs/AlGaAs heterostructure designed to achieve sharp confinement. When measuring conductance as a function of gate voltage and applying a small finite bias, we observe an intermediate conductance plateau with G = ½ e2/h. This plateau is a robust feature, being observed in multiple QPCs, and exists over a significant range of magnetic field, gate voltage, and source-drain bias. Using a simple model which considers scattering and equilibration between counterpropagating edge modes, we have found that this half-integer plateau is consistent with full reflection of an inner counterpropagating -1/3 edge mode while the outer integer mode is fully transmitted. In a QPC fabricated on a standard structure which is expected to have a soft confining potential, we instead observe an intermediate plateau at G = 1/3 e2/h, which is consistent with a theoretically predicted transition to an edge reconstructed state when the confining potential becomes soft.

*This work is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under award number DE-SC0020138.

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Presenters

  • Michael J Manfra

    • Purdue University, Microsoft Quantum Purdue
    • Purdue University
    • Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA; Microsoft Quantum Lab, Purdue University, West Lafayette, IN, USA
    • Physics and Astronomy, Purdue University
    • Department of Physics and Astronomy, Birck Nanotechnology Center, School of Electrical and Computer Engineering and Microsoft Quantum Lab West Lafayette, Purdue University
    • Department of Physics and Astronomy and Nanotechnology Center Purdue University, Microsoft Quantum Lab West Lafayette
    • Department of Physics and Astronomy, Birck Nanotechnology Center, School of Materials Engineering and School of Electrical and Computer Engineering, Purdue University

Authors

  • James R Nakamura

    • Purdue University

  • Shuang Liang

    • Purdue University

  • Geoffrey C Gardner

    • Purdue University

  • Michael J Manfra

    • Purdue University, Microsoft Quantum Purdue
    • Purdue University
    • Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA; Microsoft Quantum Lab, Purdue University, West Lafayette, IN, USA
    • Physics and Astronomy, Purdue University
    • Department of Physics and Astronomy, Birck Nanotechnology Center, School of Electrical and Computer Engineering and Microsoft Quantum Lab West Lafayette, Purdue University
    • Department of Physics and Astronomy and Nanotechnology Center Purdue University, Microsoft Quantum Lab West Lafayette
    • Department of Physics and Astronomy, Birck Nanotechnology Center, School of Materials Engineering and School of Electrical and Computer Engineering, Purdue University