  We evaluate the performance of two-way quantum repeater chains with
sequential entanglement swapping. Within the analysis we consider memory
decoherence, gate imperfections, and imperfect link-level entanglement
generation. Our main results include closed-form expressions for the average
entanglement fidelity of the generated end-to-end entangled states. We
generalize previous findings for the one-shot fidelity analysis and study the
case where repeater chains serve end-to-end requests continuously. We provide
solutions to the continuous request scenario by combining results from quantum
information theory and queuing theory. Finally, we apply the formulas obtained
to analyze the impacts of hardware parameters, i.e., coherence times and gate
fidelity, and distance on the entanglement fidelity and secret key rate of
homogeneous quantum repeater chains.
