Scientists conducted the experiment which adopted a GHZ state and a passive scheme to realize the selective Bell measurement in the repeater nodes. By manipulating a 12-photon interferometer, they implemented a 2×2 parallel all-photonic quantum repeater, and observed an 89% enhancement of entanglement-generation rate over standard parallel entanglement swapping.
These results provided a new approach to design quantum repeaters with efficient single-photon sources and photonic graph states, and suggested that the all-photonic scheme represents an alternative path towards realizing practical quantum repeaters.
In the future, the research team will be devoted to combining the all-photonic scheme with the matter-memory-based scheme. These two schemes are important parallel research directions towards achieving a practical quantum repeater. By doing so, the repeater graph state (RGS) can relax the requirement of long coherent time of quantum memory, while a quantum memory can reduce the requirement of large size for the RGS.
The successful demonstration of all-photonic quantum repeater suggests that the quantum memory is no longer a necessary condition for building a quantum repeater, which opens up a new way for the research on long-distance quantum communications and networks.
Experimental set-up. (Image by PAN Jianwei’s team)
Jane FAN Qiong
University of Science and Technology of China
52 Sanlihe Rd., Xicheng District,
Beijing, China (100864)