Academician Pan Jianwei and Bao Xiaohui of the University of Science and Technology of China combined the Reedberg interaction with the efficient single-photon interface technology to successfully prepare multiphoton entanglement based on the Reedberg superatoms for the first time, laying the foundation for applications such as unidirectional quantum relay. The results were published in Nature Photonics on August 11.
Schematic diagram of the experimental protocol Courtesy of the University of Science and Technology of China
Multiphoton entanglement has important applications in quantum computing, quantum communication, and quantum precision measurements. In the past, the main preparation method of multiphoton entanglement was to use the parametric downconversion process within nonlinear crystals. However, in the parametric process, the probability of each photon generation is low, and the probability of multiple photon generation is lower, resulting in a faster decrease in brightness when it expands to more photons. Using the deterministic advantages of single quantum systems, sequential generation of multiple correlated single photons is another important way to prepare multiphoton entanglement. This protocol is very resource-efficient and has higher scalability in principle.
Previous experiments have demonstrated the principle of this scheme in systems such as quantum dots, but the scalability of photon numbers has not exceeded that of traditional parameter conversion experiments. Atomic synthesis is an important physical system of quantum storage. By introducing the Reedberg interaction, the atomic system is synthesized into a superatomic, making deterministic manipulation of quantum states possible. Reedberg superatoms have the dual advantages of both single-atom systems and atomic synthesis systems, and have advantages in photonic interfaces and entanglement preparation.
In order to realize the preparation of multiphoton entanglement based on Reedberg superatoms, the research group of Pan Jianwei and Bao Xiaohui has developed the coupling technology of superatomics and optical cavities in recent years, and built an efficient single-photon interface for Reedberg superatoms, with the highest single-photon output rate reaching 44%.
On this basis, the research team successfully prepared three to six photon GHZ entanglement using the interaction between the two Reedberg states and using alternating readout, and the probability of each photon increase was 27%, which was better than the previous multiphoton entanglement experiment.
The work demonstrates the important advantages of Reedberg superatoms in the preparation of photon entanglement, laying the foundation for the subsequent generation of more photon entanglement and applications to tasks such as unidirectional quantum relay and unidirectional quantum computing. (Source: China Science Daily Wang Min)
Related paper information:https://doi.org/10.1038/s41566-022-01054-3