Heralded Entanglement of Single Rare-Earth Ion Qubits

Photon-based entanglement distribution is a critical requirement for quantum networking, enabling secure communication and distributed quantum computing. Solid-state defects have emerged as leading candidates for network nodes due to their compatibility with scalable device engineering and the presence of nuclear spins for local quantum processing. Recently we have demonstrated key milestones toward this application using single ¹⁷¹Yb ions in YVO₄, coupled to a nanophotonic cavity. These include coherent optical and spin control, long-term quantum information storage, single-shot readout and a nuclear ancilla qubit.



In this talk we demonstrate entanglement of two spectrally distinguishable ¹⁷¹Yb qubits in a single cavity. This is achieved with a single photon heralding protocol and frequency erasure via high-resolution detection of the photon emission time. The random quantum phase generated by the stochastic emission process is corrected in real-time, enabling preparation of a deterministic spin-entangled state. The narrow optical inhomogeneous distribution of these emitters (200MHz) enables any-to-any connectivity in a scalable fashion. Furthermore, we implement an optical dynamical decoupling protocol to boost the entanglement rate. These results showcase single rare-earth ions as a promising platform for the future quantum internet.

[1] Kindem, Ruskuc et al. Nature, 580, 201 (2020)

[2] Ruskuc et al. Nature, 602, 408 (2022)