Charge qubit dynamics in a double quantum dot coupled to phonons

TL;DR

This paper theoretically investigates charge qubit dynamics in a double quantum dot coupled to phonons, analyzing decoherence mechanisms and comparing perturbation methods to understand phonon-induced effects.

Contribution

It introduces a perturbation treatment based on a unitary transformation to analyze charge qubit-phonon interactions and predicts a potential decoupling mechanism.

Findings

Deformation potential and piezoelectric couplings contribute similarly to decoherence in certain regimes.

Explicit dynamical tunneling current is derived.

A possible decoupling mechanism for phonons is proposed.

Abstract

The dynamics of charge qubit in a double quantum dot coupled to phonons is investigated theoretically in terms of a perturbation treatment based on a unitary transformation. The dynamical tunneling current is obtained explicitly. The result is compared with the standard perturbation theory at Born-Markov approximation. The decoherence induced by acoustic phonons is analyzed at length. It is shown that the contribution from deformation potential coupling is comparable to that from piezoelectric coupling in small dot size and large tunneling rate case. A possible decoupling mechanism is predicted.