Coherent driving of direct and indirect excitons in a quantum dot molecule

Quantum dot molecules (QDMs) are one of the few quantum light sources that promise deterministic gener-ation of one-and two-dimensional photonic graph states. The proposed protocols rely on coherent excitation of the tunnel-coupled and spatially indirect exciton states. Here, we demonstrate power-dependent Rabi oscillations of direct excitons, spatially indirect excitons, and excitons with a hybridized electron wave function. An off-resonant detection technique based on phonon-mediated state transfer allows for spectrally filtered detection under resonant excitation. Applying a gate voltage to the QDM device enables a continuous transition between direct and indirect excitons and, thereby, control of the overlap of the electron and hole wave function. This does not only vary the Rabi frequency of the investigated transition by a factor of approximate to 3, but also allows to optimize graph state generation in terms of optical pulse power and reduction of radiative lifetimes.

Automated summary

Quantum dot molecules (QDMs) are capable of generating one-and two-dimensional photonic graph states deterministically. In this study, power-dependent Rabi oscillations of direct excitons, spatially indirect excitons, and excitons with a hybridized electron wave function are demonstrated. An off-resonant detection technique based on phonon-mediated state transfer allows for spectrally filtered detection under resonant excitation. The application of a gate voltage to the QDM device enables continuous transition between direct and indirect excitons, providing control over the overlap of the electron and hole wave function and optimization of graph state generation.