physica status solidi (b)
Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Editor: Stefan Hildebrandt (Editor-in-Chief), Sabine Bahrs (Deputy Editor)
Online ISSN: 1521-3951
Front Cover (Phys. Status Solidi B 9/2010)
In their Editor's Choice article on pp. 2147–2154, Juliane Danckwerts et al. investigate the effect of Coulomb interaction on the applicability of quantum gates on a system of two Coulomb-coupled quantum dots. They calculate the fidelity for a single- and a two-qubit gate and the creation of Bell states in the system, taking into account the influence of radiative damping. The cover picture shows the energy level scheme of a coupled two-quantum dot system and the change of the Bloch vector during the first step of Bellstate generation. It is found that the considered gates based on the Coulomb interaction can be implemented with input state-dependent errors that strongly depend on the Coulomb coupling strength. Error rates can be kept in the range of 10−3 for a suitable choice of the Coulomb matrix elements, determined by material and external field parameters. Radiative dephasing is a more serious problem and typically leads to larger errors on the order of 10−2 for the considered gates. However, the specific task of the generation of a maximally entangled Bell state can be accomplished with error rates in the range of 10−3, even in the presence of radiative dephasing. The results are of importance also for other proposals of quantum information processing with quantum dots, in particular the widely investigated schemes utilizing electron spin states.