Towards entanglement distillation between atomic ensembles using high-fidelity spin operations

• Published in: Communications physics Vol. 5; no. 1; pp. 1 - 9
• Main Authors: Liu, Chao, Tu, Tao, Li, Pei-Yun, Liu, Xiao, Zhu, Xing-Yu, Zhou, Zong-Quan, Li, Chuan-Feng, Guo, Guang-Can
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 22.03.2022; Nature Publishing Group; Nature Portfolio
• Subjects: 639/766/483/2802; 639/766/483/481; Accuracy; Atoms & subatomic particles; Communication; Crystal structure; Distillation; Doped crystals; Efficiency; Electron spin; Entangled states; Filtration; Physics; Physics and Astronomy; Quantum entanglement; Quantum phenomena; Qubits (quantum computing); Rare earth elements; Repeaters
• ISSN: 2399-3650; 2399-3650
• DOI: 10.1038/s42005-022-00835-0

Entanglement distillation is an essential ingredient for long-distance quantum communication. However, owing to their demanding requirements, integrating such entanglement distillation processing in scalable quantum devices remains an outstanding challenge. Here we propose the implementation of the filtering protocol in atomic ensembles, which are promising candidates for building quantum repeater nodes, and analyze the boost entanglement distribution rate considering different scenarios. Moreover, we demonstrate the key step of this approach with a proof-of-principle experiment in a rare-earth-ion-doped crystal ( 143 Nd 3+ :Y 2 SiO 5 ). Leveraging its multi-level structure and long-lived coherence, spin manipulations are implemented with an average fidelity exceeding 97.2%, leading to the preparation of entanglement between the electron and nuclear spins with a concurrence of 0.75 with a sample temperature of 100 mK. The versatility, robustness, and potential scalability of our proposal contribute to the construction of quantum repeaters and quantum networks based on atomic ensembles. Entanglement distillation is essential for quantum information applications, generating remote entanglement in repeater units. Here, a filtering protocol using two-qubit entangled states in an atomic ensemble is proposed and demonstrated in a proof-of-principle experiment.