Decoherence in a Double-Dot Aharonov-Bohm Interferometer

TL;DR

This paper investigates decoherence in a double quantum dot Aharonov-Bohm interferometer using nonperturbative methods, confirming that coherence is restored at zero frequency despite perturbative expectations.

Contribution

It applies the numerical renormalization group to study ac transport and decoherence, distinguishing renormalization effects from decoherence in a realistic quantum dot model.

Findings

Coherence is restored in the dc limit despite perturbative predictions.

Finite frequency transport shows clear signatures of decoherence effects.

The model distinguishes renormalization from decoherence phenomena.

Abstract

Coherence in electronic interferometers is typically believed to be restored fully in the limit of small voltages, frequencies and temperatures. However, it is crucial to check this essentially perturbative argument by nonperturbative methods. Here, we use the numerical renormalization group to study ac transport and decoherence in an experimentally realizable model interferometer, a parallel double quantum dot coupled to a phonon mode. The model allows to clearly distinguish renormalization effects from decoherence. We discuss finite frequency transport and confirm the restoration of coherence in the dc limit.