Pan Jianwei's team at CSU achieves multi-photon entanglement based on Riedberg superatoms
Recently, Pan Jianwei and Xiaohui Bao of the University of Science and Technology of China (USTC), combining Riedberg interactions with efficient single-photon interface technology, have successfully prepared multi-photon entanglement based on Riedberg superatoms for the first time, laying the foundation for applications such as one-way quantum relay. The related research results were published in Nature Photonics on Aug. 11.
Multi-photon entanglement has important applications in quantum computing, quantum communication, and quantum precision measurements. Previously, the main preparation method for multi-photon entanglement was to use a parametric down-conversion process within a nonlinear crystal. However, the parametric process, in which the photons are probabilistically generated, leads to a faster decrease in brightness as it expands to more photons. The sequential generation of multiple associated single photons using the deterministic advantage of the single-qubit system is another important way to prepare multi-photon entanglement. This scheme is very economical in terms of experimental resources and has higher scalability in principle.
Previous experiments have demonstrated the principle of this scheme in systems such as quantum dots, however, the scalability in terms of photon number has not surpassed that of conventional parametric down-conversion experiments. The atomic system synthesis is an important physical system for quantum storage. By introducing the Riedberg interaction, the atomic heterodyne becomes a superatom, making deterministic quantum state manipulation possible. The Riedberg superatom has the advantages of both the single-atom system and the atomic heterodyne system, and has advantages in photonic interfaces and entanglement preparation.
Figure: Schematic diagram of the experimental scheme
To realize the preparation of multi-photon entanglement based on Riedberg superatoms, the research group of Jianwei Pan and Xiaohui Bao has developed the coupling technique between superatoms and optical cavities in recent years [Optica 9, 853 (2022)], and constructed an efficient single-photon interface for Riedberg superatoms, and the highest single-photon output rate has reached 44%. Based on this, the group has successfully prepared three- to six-photon GHZ entanglement with a 27% probability per additional photon, superior to previous multi-photon entanglement experiments, using interactions between two Reedeburg states with alternating readout [Phys. Rev. Lett. 128, 060502 (2022)].
This work demonstrates the important advantages of Riedberg superatoms for photon entanglement preparation, and lays the foundation for subsequent generation of more photon entanglements and their application to tasks such as one-way quantum relaying and one-way quantum computing.
PhD student Chaowei Yang is the first author of the paper. This work was supported by the Ministry of Science and Technology, Anhui Province, the National Natural Science Foundation of China, and Hefei National Laboratory.
Article links:
https://www.nature.com/articles/s41566-022-01054-3
