Google Demonstrates 99.99% Logical Fidelity in Willow Test

Google Quantum AI demonstrated 99.99% logical fidelity in prepared T-states on its Willow processor in a study published Thursday, Oct. 15, reporting a 40-fold reduction in errors.

The fidelity figure measures how accurately the experiment prepared the T-states, not the accuracy of an entire quantum computer. Magic states help quantum computers perform operations needed for universal computing.

The experiment transferred cultivated states from a distance-3 color code to a distance-5 surface code. It retained 8% of attempts. Larger-scale demonstrations are still needed.

Blockchain networks have their own post-quantum plans. Ethereum’s roadmap targets quantum-resistant infrastructure across its execution, consensus and data layers by December 2029. Algorand’s roadmap sets native post-quantum accounts for 2026 and broader resilience for 2027.