Silicon Quantum Computing reached 99.99% two-qubit fidelity in December 2025, matching the trapped-ion benchmark and marking a key credibility gain for silicon-spin hardware.
Four silicon-spin companies—Diraq, Quantum Motion, SQC and Photonic Inc—were selected for DARPA's Quantum Benchmarking Initiative Stage B in November 2025, the strongest showing of any single modality.
That progress is tied to structural advantages: silicon-spin qubits are built on existing 300mm CMOS lines, are about 1,000 times smaller than superconducting transmons, and can run as warm as 1 Kelvin.
The trade-off is scale today: leading silicon-spin systems still run only 6 to 12 qubits, even as Quantum Motion validated a 1,024-dot array and SQC patterned 250,000 qubit registers in eight hours.
With funding across the field above $900 million entering 2026, silicon spin is emerging as a late-starting quantum approach with one of the clearest paths to mass manufacturing.
Can silicon's manufacturing power overcome its lag in the crucial quantum error correction race against established rivals?
With million-qubit chips on the roadmap, can the global supply chain for ultra-pure silicon scale fast enough to meet demand?
As 'hot' qubits promise cheaper quantum computers, what hidden performance trade-offs could stall their widespread adoption?
From 99.99% Gate Fidelity to Q-Day: SQC, DARPA, and the Urgent Path to Commercial Quantum Supremacy
Overview
Silicon Quantum Computing (SQC) has set a new standard in the field by achieving 99.99% two-qubit gate fidelity in its silicon-based quantum processors, a milestone that builds on earlier successes in controlling multiple nuclear spin qubits within a single register. This breakthrough not only marks a major step forward for silicon quantum computing but also addresses the challenge of connecting multiple registers without losing fidelity. High-performance qubits like these are crucial because they reduce the overhead needed for quantum error correction, bringing the industry closer to practical, fault-tolerant quantum systems and paving the way for scalable, robust quantum computers.