Performance analysis of quantum repeaters enabled by deterministically generated photonic graph states

By encoding logical qubits into specific types of photonic graph states, one can realize quan-tum repeaters that enable fast entanglement distribution rates approaching classical com-munication. However, the generation of these photonic graph states requires a formidable re-source overhead using traditional approaches based on linear optics. Overcoming this chal-lenge, a number of new schemes have been proposed that employ quantum emitters to de-terministically generate photonic graph states. Although these schemes have the potential to significantly reduce the resource cost, a sys-tematic comparison of the repeater perfor-mance among different encodings and different generation schemes is lacking. Here, we quan-titatively analyze the performance of quantum repeaters based on two different graph states, i.e. the tree graph states and the repeater graph states. For both states, we compare the performance between two generation schemes, one based on a single quantum emitter coupled to ancillary matter qubits, and one based on a single quantum emitter coupled to a delayed feedback. We identify the numerically optimal scheme at different system parameters. Our analysis provides a clear guideline on the selec-tion of the generation scheme for graph-state -based quantum repeaters, and lays out the pa-rameter requirements for future experimental realizations of different schemes.