Zusammenfassung
Quantum repeaters -- important components of a scalable quantum internet --
enable the entanglement to be distributed over long distances. The standard
paradigm for a quantum repeater relies on a necessary demanding requirement of
quantum memory. Despite significant progress, the limited performance of
quantum memory makes practical quantum repeaters still a great challenge.
Remarkably, a proposed all-photonic quantum repeater avoids the need for
quantum memory by harnessing the graph states in the repeater nodes. Here we
perform an experimental demonstration of an all-photonic quantum repeater using
linear optics. By manipulating a 12-photon interferometer, we implement a
2-by-2 parallel all-photonic quantum repeater, and observe an 89% enhancement
of entanglement-generation rate over the standard parallel entanglement
swapping. These results open a new way towards designing repeaters with
efficient single-photon sources and photonic graph states, and suggest that the
all-photonic scheme represents an alternative path -- parallel to that of
matter-memory-based schemes -- towards realizing practical quantum repeaters.
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