  Electrically controllable quantum-dot molecules (QDMs) are a promising
platform for deterministic entanglement generation and, as such, a resource for
quantum-repeater networks. We develop a microscopic open-quantum-systems
approach based on a time-dependent Bloch-Redfield equation to model the
generation of entangled spin states with high fidelity. The state preparation
is a crucial step in a protocol for deterministic entangled-photon-pair
generation that we propose for quantum repeater applications. Our theory takes
into account the quantum-dot molecules' electronic properties that are
controlled by time-dependent electric fields as well as dissipation due to
electron-phonon interaction. We quantify the transition between adiabatic and
non-adiabatic regimes, which provides insights into the dynamics of adiabatic
control of QDM charge states in the presence of dissipative processes. From
this, we infer the maximum speed of entangled-state preparation under different
experimental conditions, which serves as a first step towards simulation of
attainable entangled photon-pair generation rates. The developed formalism
opens the possibility for device-realistic descriptions of repeater protocol
implementations.
