Heterogeneous Ion-SiV Link Hits 1.03 kHz Bell-Pair Rate with 87.9% Fidelity

The experiment used a single detected photon to herald entanglement between a trapped ¹³⁸Ba⁺ ion and an SiV⁻ center in a diamond cavity. A 493 nm photon from the ion was converted to 737 nm, reflected from the cavity, and detected, with all conversion losses included in the rate. This photonic interface produced one Bell pair per millisecond, matching the cycle time of planned trapped-ion processors and exceeding the fastest prior ion–ion photonic link by a factor of four.

The work addresses a central bottleneck in modular quantum computing: photon loss that caps entanglement rates between separate modules. By bridging atomic and solid-state qubits with a switchable long-range link, the result demonstrates that heterogeneous systems can reach speeds previously limited to homogeneous platforms. The 87.9% fidelity remains below fault-tolerance thresholds but is high enough to test error-correction primitives on near-term hardware.

Key limitations include the preprint status and modest sample of calibration runs; larger statistics and in-situ benchmarking against two-ion links would strengthen claims. Integration with real-time feed-forward and multi-node scaling remain untested. If replicated, the approach could enable distributed algorithms whose gate times are set by communication rather than local coherence.