Multiplexed entanglement of multi-emitter quantum network nodes

Ruskuc, A.; Wu, C.-J.; Green, E.; Hermans, S. L. N.; Pajak, W.; Choi, J.; Faraon, A.

doi:10.1038/s41586-024-08537-z

Published March 6, 2025 | Version Supplemental material

Journal Article Open

Multiplexed entanglement of multi-emitter quantum network nodes

1. California Institute of Technology
2. Harvard University
3. Stanford University

Quantum networks that distribute entanglement among remote nodes will unlock transformational technologies in quantum computing, communication and sensing. However, state-of-the-art networks use only a single optically addressed qubit per node; this constrains both the quantum communication bandwidth and memory resources, greatly impeding scalability. Solid-state platforms provide a valuable resource for multiplexed quantum networking in which multiple spectrally distinguishable qubits can be hosted in nano-scale volumes. Here we harness this resource by implementing a two-node network consisting of several rare-earth ions coupled to nanophotonic cavities. This is accomplished with a protocol that entangles distinguishable ¹⁷¹Yb ions through frequency-erasing photon detection combined with real-time quantum feedforward. This method is robust to slow optical frequency fluctuations occurring on timescales longer than a single entanglement attempt: a universal challenge amongst solid-state emitters. We demonstrate the enhanced functionality of these multi-emitter nodes in two ways. First, we mitigate the bottlenecks to the entanglement distribution rate through multiplexed entanglement of two remote ion pairs. Second, we prepare multipartite W-states comprising three distinguishable ions as a resource for advanced quantum networking protocols. These results lay the groundwork for scalable quantum networking based on rare-earth ions.

Copyright and License

Acknowledgement

This work was funded primarily by the Air Force Office of Scientific Research (grant no. FA9550-22-1-0178) and the Institute of Quantum Information and Matter, an NSF Physics Frontiers Center (PHY-1733907) with support from the Moore Foundation. We also acknowledge funding from NSF 2210570 and NSF 2137984. The device nanofabrication was performed at the Kavli Nanoscience Institute at the California Institute of Technology. A.R. acknowledges support from the Eddleman Graduate Fellowship. C.-J.W. acknowledges support from the J. Yang and Family Foundation and a Taiwanese government scholarship to study abroad. E.G. acknowledges support from the National Science Foundation Graduate Research Fellowship under grant no. 2139433 and the National Gem Consortium. S.L.N.H. acknowledges support from the AWS Quantum Postdoctoral Fellowship. J.C. acknowledges support from the Terman Faculty Fellowship at Stanford. We thank E. Paul for help with the experimental setup; J. Thompson and M. T. Uysal for discussion related to the entanglement protocol; J. Borregaard, D. Lukin, T. Xie, M. Lei, R. Fukumori, E. Liu and B. Grinkemeyer for useful discussions; and J. Rochman, T. Zheng, S. Gu and B. Baspinar for help with nanofabrication.

Contributions

These authors contributed equally: A. Ruskuc, C.-J. Wu.

A.R. and A.F. conceived the experiments. A.R., C.-J.W. and E.G. fabricated the devices. A.R., C.-J.W. and W.P. performed the experiments and analysed the data. A.R., C.-J.W., S.L.N.H. and J.C. contributed to the interpretation of the data. A.R., C.-J.W. and A.F. wrote the paper with input from all authors. A.F. supervised the project.