Dephasing of an Electronic Two-Path Interferometer

TL;DR

This study investigates dephasing in an electronic Mach-Zehnder interferometer within the integer quantum Hall regime, revealing how interactions and potential influence visibility and phase coherence, with implications for observing fractional charge interference.

Contribution

It provides new insights into the dephasing mechanisms and the role of interactions in electronic interferometers at different filling factors, especially near unity.

Findings

Visibility quenched near filling factor one

Drift velocity saturated at minimal value around unity

Phase randomization likely causes dephasing in fractional regime

Abstract

This work was motivated by the quest for observing interference of fractionally charged quasi particles. Here, we study the behavior of an electronic Mach-Zehnder interferometer (MZI) at the integer quantum Hall effect (IQHE) regime at filling factors greater than one. Both the visibility and the drift velocity were measured, and were found to be highly correlated as function of filling factor. As the filling factor approached unity, the visibility quenched, not to recover for filling factors smaller than unity. Alternatively, the velocity saturated around a minimal value at unity filling factor. We highlight the significant role interactions between the interfering edge and the bulk play, as well as that of the defining potential at the edge. Shot noise measurements suggest that phase-averaging (due to phase randomization), rather than single particle decoherence, is likely to be the cause of the dephasing in the fractional regime.