Measurement of electronic Fabry-Perot interferometers optimized for high edge state velocity

ORAL

Abstract

Electronic Fabry-Perot interferometers may be used to probe the properties of electrons and quasiparticles in the quantum Hall regime. The visibility of interference is limited by finite coherence time and edge state velocity. We present two methods for enhancing the edge state velocity in GaAs/AlGaAs heterostructures by increasing the sharpness of the confining potential at the edge. The first method involves a gating scheme utilizing a combination of negatively biased gates to define the interference path and positively biased helper gates; the abrupt interface between positive and negative gate bias yields a sharp edge potential in the 2DEG. The second method involves novel heterostructures with parallel conducting quantum wells positioned with a short setback from the primary quantum well; when negative bias is applied to surface gates, the proximity of the additional quantum wells results in sharp confining potential in the primary quantum well. The devices are measured in a dilution refrigerator at T~10mK in high magnetic field. Efforts are underway to utilize these interferometers in the fractional quantum Hall regime, where interference may be used to probe exotic quasiparticle statistics.

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Presenters

  • James Nakamura

    Physics, Purdue University, Purdue Univ

Authors

  • James Nakamura

    Physics, Purdue University, Purdue Univ

  • Qi Qian

    Physics, Purdue University, Purdue University, Purdue Univ

  • Saeed Fallahi

    Purdue University, Physics, Purdue University, Purdue Univ, Department of Physics and Astronomy, and School of Materials Engineering, and School of Electrical and Computer Engineering, Purdue University

  • Robert Willett

    Nokia Bell Labs, Nokia - Bell Labs

  • Geoffrey Gardner

    Department of Physics and Astronomy and Station Q Purdue, Purdue University, Microsoft Station Q Purdue, Birck Nanotechnology Center, Purdue University, Purdue University, Station Q Purdue, Purdue Univ, Purdue University, Physics and Astronomy, Purdue University

  • Michael Manfra

    Department of Physics and Astronomy and Station Q Purdue, Purdue University, Department of Physics and Astronomy and Microsoft Station Q Purdue, Purdue University, Purdue University, Physics, Purdue University, Purdue University, Station Q Purdue, Purdue Univ, Department of Physics and Astronomy, and School of Materials Engineering, and School of Electrical and Computer Engineering, Purdue University, Physics and Astronomy, Purdue University, Dept. of Physics and Astronomy, Purdue Univ