Fidelity of optically controlled single- and two-qubit operations on Coulomb-coupled quantum dots

Abstract

We investigate the effect of the Coulomb interaction on the applicability of quantum gates on a system of two Coulombcoupled quantum dots. We calculate the fidelity for a single-and a two-qubit gate and the creation of Bell states in the system. The influence of radiative damping is also studied. We find that the application of quantum gates based on the Coulomb interaction leads to significant input state-dependent errors which strongly depend on the Coulomb coupling strength. By optimizing the Coulomb matrix elements via the material and the external field parameters, error rates in the range of 10 À3 can be reached. Radiative dephasing is a more serious problem and typically leads to larger errors on the order of 10 À2 for the considered gates. In the specific case of the generation of a maximally entangled Bell state, error rates in the range of 10 À3can be achieved even in the presence of radiative dephasing.

Inductive equation of motion approach for a semiconductor QD‐QED: Coherence induced control of photon statistics

“…Since semiconductor quantum dots (QD) show atom-like emission properties, due to quantum confinement, QD-QED includes typical cavity-QED phenomena like vacuum Rabi splitting and oscillations [5,7,8]. Semiconductor cavity systems (micropillars, photonic crystal nanocavities [9-11]) involving the interaction with semiconductor QDs, are promising candidates for the technological realization of single photon emitters, qubits, or entangled photon sources [12][13][14][15].In dependence on the material system, also lambda(L)-type QDs [16,17] are investigated, aiming at the controlled modulation of photon statistics via strong-coupling and quantum coherence effects [18]. Due to the discrete level scheme of the QD, effects like lasing without inversion (LWI) or electromagnetically induced transparency (EIT) can be achieved [19,20].…”