Phonon Decoherence of a Double Quantum Dot Charge Qubit

TL;DR

This paper investigates phonon-induced decoherence in a double quantum dot charge qubit, finding that phonon effects are weaker than previously thought and highlighting other dominant decoherence mechanisms.

Contribution

It provides a refined calculation of phonon decoherence rates considering form factors, showing they are less significant than earlier predictions.

Findings

Phonon decoherence rates are 10-100 times weaker than prior estimates.

Q-factor depends on temperature, dot size, and interdot coupling.

Other mechanisms likely dominate decoherence in experiments.

Abstract

We study decoherence of a quantum dot charge qubit due to coupling to piezoelectric acoustic phonons in the Born-Markov approximation. After including appropriate form factors, we find that phonon decoherence rates are one to two orders of magnitude weaker than was previously predicted. We calculate the dependence of the Q-factor on lattice temperature, quantum dot size, and interdot coupling. Our results suggest that mechanisms other than phonon decoherence play a more significant role in current experimental setups.