Dresden 2009 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 23: Transport in high magnetic field/quantum-Hall-effect

HL 23.4: Talk

Tuesday, March 24, 2009, 14:45–15:00, BEY 154

Electron interference and dephasing in electronic Mach-Zehnder interferometer — Leonid Litvin, •Andreas Helzel, Hans-Peter Tranitz, Werner Wegscheider, and Christoph Strunk — Intitut für experimentelle und angewandte Physik, Universität Regensburg, D-93040 Regensburg, Deutschland

We study the visibility of Aharonov-Bohm interference in an electronic Mach-Zehnder interferometer (MZI) in the integer quantum Hall regime. The visibility is controlled by the filling factor ν and is observed only between ν ≈ 2.0 and 1.0, with an unexpected maximum near ν=1.5. Three energy scales extracted from the temperature and voltage dependences of the visibility change in a very similar way with the filling factor, indicating that the different aspects of the interference depend sensitively on the local structure of the compressible and incompressible strips forming the quantum Hall edge channels. The superposition of confining potentials, produced by gate of quantum point contact (QPC) and disorder potential from doping impurities, results in the formation of inadvertent quantum dot (QD) in one arm of interferometer. The phase of the QD transmission amplitude was directly observed in the MZI. This implies, that charge state of QD can be measured by detecting its transmission (reflection) phase with the interferometer, and may be used as more sensitive detectors for QD state, than the currently used QPCs.