Google cuts quantum errors 40-fold: Is Bitcoin at risk?

Google has demonstrated a 40-fold reduction in quantum computing errors using its Willow processor, advancing a technology that researchers believe could eventually challenge the cryptography protecting Bitcoin. Summary Google reduced quantum computing errors approximately 40-fold using magic state cultivation on its Willow processor. Google’s researchers achieved 99.99% logical fidelity while testing purified quantum states on real computing hardware. Glassnode estimated 6.04 million BTC had exposed public keys, representing 30.2% of mined Bitcoin. Google’s earlier research estimated future cryptographic attacks could require fewer than 500,000 physical quantum qubits. Coinbase published Bitcoin security recommendations on October 13, addressing migration challenges and vulnerable legacy coins. Google announced the results on October 15, 2026, following the publication of its research in the scientific journal Science. The experiment used a technique called magic state cultivation to produce quantum states with 99.99% logical fidelity, or accuracy, under the researchers’ testing method. The achievement addresses a technical problem that has limited efforts to build reliable quantu...