Sandia and Quantinuum's Helios Hits 99.9975% Single-Qubit Fidelity in Peer-Reviewed Results

Sandia National Laboratories highlighted on August 27, 2026 the peer-reviewed results of its four-year collaboration with Quantinuum, published in Nature, benchmarking the performance of Quantinuum's 98-qubit commercial trapped-ion system, Helios.

Exceptionally High Fidelity Numbers

• Single-qubit gate fidelity of 99.9975% — an average infidelity of just 2.5×10⁻⁵
• Two-qubit gate fidelity of 99.921% — an average infidelity of 7.9×10⁻⁴
• State Preparation and Measurement (SPAM) fidelity of 99.967%

The paper describes Helios as the company's largest and most reliable quantum computer to date, with these figures representing the kind of precision needed to move quantum computing from experimental demonstrations toward practical, error-corrected applications.

A Four-Year Government-Industry Partnership

Sandia has evaluated and certified Helios's performance under a long-standing Cooperative Research and Development Agreement, renewed in May 2026. Sandia contributed new benchmarking methodologies specifically for measuring mid-circuit measurements — a capability that is critical for structural quantum error correction and central to the Department of Energy's broader goal of achieving fault-tolerant quantum computing systems.

Why Mid-Circuit Measurement Benchmarking Matters

Sandia verified Helios's system-level fidelity using volumetric benchmarks, including random Clifford circuits containing automated mid-circuit measurements and resets, evaluating the hardware's cross-talk boundaries and stabilizer-tracking capabilities — specific, technical validation work that underpins any credible claim of progress toward error-corrected quantum computing, rather than a marketing-driven fidelity number alone.

What This Means for Quantum Computing's Timeline

Independent, peer-reviewed, government-lab-certified benchmarking — rather than a vendor's own internal claims — is a specific, credible signal that trapped-ion quantum hardware is closing in on the fidelity thresholds fault-tolerant error correction requires, a useful data point for organizations tracking when quantum computing might move from research curiosity to practical enterprise tool.