Realization of a crosstalk-avoided quantum network node using dual-type qubits of the same ion species

• Published in: Nature communications Vol. 15; no. 1; pp. 204 - 7
• Main Authors: Feng, L., Huang, Y.-Y., Wu, Y.-K., Guo, W.-X., Ma, J.-Y., Yang, H.-X., Zhang, L., Wang, Y., Huang, C.-X., Zhang, C., Yao, L., Qi, B.-X., Pu, Y.-F., Zhou, Z.-C., Duan, L.-M.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 03.01.2024; Nature Publishing Group; Nature Portfolio
• Subjects: 639/766/400/3925; 639/766/483/2802; 639/766/483/481; Coding; Communication; Cooling; Crosstalk; Humanities and Social Sciences; Hyperfine structure; Ions; Lasers; multidisciplinary; Photons; Quantum computing; Quantum entanglement; Quantum phenomena; Qubits (quantum computing); Radiation; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-44220-z

Generating ion-photon entanglement is a crucial step for scalable trapped-ion quantum networks. To avoid the crosstalk on memory qubits carrying quantum information, it is common to use a different ion species for ion-photon entanglement generation such that the scattered photons are far off-resonant for the memory qubits. However, such a dual-species scheme can be subject to inefficient sympathetic cooling due to the mass mismatch of the ions. Here we demonstrate a trapped-ion quantum network node in the dual-type qubit scheme where two types of qubits are encoded in the S and F hyperfine structure levels of 171 Yb + ions. We generate ion photon entanglement for the S -qubit in a typical timescale of hundreds of milliseconds, and verify its small crosstalk on a nearby F -qubit with coherence time above seconds. Our work demonstrates an enabling function of the dual-type qubit scheme for scalable quantum networks. In ion-photon quantum network platforms, usually memory qubits and communication qubits are encoded in ions of different species. Here, instead, the authors show how to realise ion-photon entanglement within the same-species-dual-encoding scheme.