Tuning Energy Relaxation along Quantum Hall Channels

TL;DR

This paper demonstrates experimental control over energy relaxation in quantum Hall edge channels at filling factor 2, revealing mechanisms that limit quantum coherence and ways to manipulate them for quantum information applications.

Contribution

It introduces a method to tune energy relaxation in quantum Hall channels and shows how to suppress inelastic processes, advancing understanding of quantum coherence preservation.

Findings

Energy relaxation can be enhanced by increasing transmission to a floating contact.

Forming a closed inner edge channel loop freezes energy exchanges in the outer channel.

Inelastic mechanisms within the outer edge channel are negligible at filling factor 2.

Abstract

The chiral edge channels in the quantum Hall regime are considered ideal ballistic quantum channels, and have quantum information processing potentialities. Here, we demonstrate experimentally, at filling factor 2, the efficient tuning of the energy relaxation that limits quantum coherence and permits the return toward equilibrium. Energy relaxation along an edge channel is controllably enhanced by increasing its transmission toward a floating ohmic contact, in quantitative agreement with predictions. Moreover, by forming a closed inner edge channel loop, we freeze energy exchanges in the outer channel. This result also elucidates the inelastic mechanisms at work at filling factor 2, informing us in particular that those within the outer edge channel are negligible.