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arXiv · 2405.13369

Realization of a crosstalk-free two-ion node for long-distance quantum networking

P. -C. Lai·Y. Wang·J. -X. Shi·Z. -B. Cui·Z. -Q. Wang·S. Zhang·P. -Y. Liu·Z. -C. Tian·Y. -D. Sun·X. -Y. Chang·B. -X. Qi·Y. -Y. Huang·Z. -C. Zhou·Y. -K. Wu·Y. Xu·Y. -F. Pu·L. -M. Duan
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Abstract

Trapped atomic ions constitute one of the leading physical platforms for building the quantum repeater nodes to realize large-scale quantum networks. In a long-distance trapped-ion quantum network, it is essential to have crosstalk-free dual-type qubits: one type, called the communication qubit, to establish an entangling interface with telecom photons; and the other type, called the memory qubit, to store quantum information immune from photon scattering under entangling attempts. Here, we report the first experimental implementation of a telecom-compatible and crosstalk-free quantum network node based on two trapped $^{40}$Ca$^{+}$ ions. The memory qubit is encoded on a long-lived metastable level to avoid crosstalk with the communication qubit encoded in another subspace of the same ion species, and a quantum wavelength conversion module is employed to generate ion-photon entanglement over a $12\,$km fiber in a heralded style. Our work therefore constitutes an important step towards the realization of quantum repeaters and long-distance quantum networks.

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P. -C. Lai, Y. Wang, J. -X. Shi, Z. -B. Cui, Z. -Q. Wang, S. Zhang, P. -Y. Liu, Z. -C. Tian, Y. -D. Sun, X. -Y. Chang, B. -X. Qi, Y. -Y. Huang, Z. -C. Zhou, Y. -K. Wu, Y. Xu, Y. -F. Pu, L. -M. Duan. 2024-05-22. Realization of a crosstalk-free two-ion node for long-distance quantum networking. https://doi.org/10.1103/physrevlett.134.070801

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