RIKEN Demonstrates High-Fidelity Simultaneous Control of Silicon Spin Qubits Above 99.9% Threshold
AI-summarised brief · reviewed before publication
RIKEN and collaborators reported simultaneous single‑qubit gates on a five‑qubit 28Si/SiGe quantum‑dot array using one shared microwave line. By identifying off‑resonant AC‑Stark shifts as the dominant source of parallel‑drive crosstalk, they introduced an N(N‑1) pairwise calibration protocol that linearly compensates phase errors. The method preserves gate fidelities above 99.9 % for all five qubits, surpassing the fault‑tolerant threshold required for quantum error correction. Idle silicon spin qubits dephase in ~10 µs, while driven qubits reach T2,R ≈ 100 µs, making concurrent operations essential for cyclic error‑correction cycles. The team also suggests that integrating back‑end‑of‑line nanomagnets could double field gradients, enabling 2–3 MHz gates and scaling to ten‑qubit modules in commercial silicon processes. The calibration requires only measurement overhead and can be automated for arrays.
💡 Why It Matters
- · Achieving >99.9 % simultaneous gate fidelity unlocks practical error‑corrected silicon processors, moving the platform from laboratory demos toward scalable manufacturing.
