Theory of the Quantum Hall Insulator

TL;DR

This paper introduces a new theoretical approach incorporating incoherent events into quantum calculations, explaining the experimental observation of the quantum Hall insulator phase and its stability with temperature and bias.

Contribution

It presents a novel theoretical framework that includes incoherent events, resolving previous contradictions and explaining the stability of the quantum Hall insulator phase.

Findings

Decoherence events stabilize the quantum Hall insulator phase.

The phase becomes more stable with increasing temperature and voltage bias.

Theoretical results align with experimental observations.

Abstract

The quantum Hall transition is one of the simplest and most studied quantum phase transitions. Nevertheless, the experimental observation of a new phase in this regime, the quantum Hall insulator, still remains a puzzle since the first report more than a decade ago, as it is in contradiction with all theoretical studies based on microscopically coherent quantum calculations. In this work we introduce into the coherent quantum theory a new ingredient - rare incoherent events, in a controlled manner. Using both direct numerical solutions and real-space renormalization, we demonstrate that these decoherence events stabilize the elusive quantum Hall insulator phase, which becomes even more stable with increasing temperature and voltage bias, in agreement with experiments.