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ZEC $1,230 Google cuts quantum errors 40-fold as Bitcoin security debate returns
Google's Willow processor reduced errors in a key quantum operation, reviving questions about Bitcoin's cryptographic defenses.
Key takeaways
- Error reduction is real. Google cut errors by 40 times and reached 99.99% logical fidelity on Willow.
- Exposure is large. Glassnode estimated 6.04 million BTC had exposed public keys, or 30.2% of mined Bitcoin.
- No attack yet. The experiment did not break Bitcoin's encryption, and the qubit estimate assumed future hardware.
What happened
Google reported a 40-fold reduction in errors for a key quantum operation using its Willow processor. The company announced the results on October 15, 2026, after publishing its research in the journal Science. The test used a technique called magic state cultivation to produce quantum states with 99.99% logical fidelity.
The method starts with a quantum state that contains errors and subjects it to repeated checks. Faulty attempts are discarded. On Willow, just 8% of states passed the checks, and researchers transferred the remaining states between two error-correction methods.
Google's earlier research estimated that future cryptographic attacks could require fewer than 500,000 physical quantum qubits. In March, Google Quantum AI researchers said a future machine might break Bitcoin's current signature protection using fewer than 500,000 physical qubits under specified hardware assumptions.
First $84.4KLatest $82.8K-2.0% over the period
Points are daily observations, not closing prices.
Why it matters
The result concerns technology that could eventually help future machines perform calculations needed to attack existing cryptographic systems. Although the experiment did not break Bitcoin's encryption, it addresses a technical problem that has limited efforts to build reliable quantum computers.
Glassnode estimated 6.04 million BTC had exposed public keys, representing 30.2% of mined Bitcoin. Blockonomi reported that about 6.9 million BTC may face exposure through already visible public keys. Coinbase published Bitcoin security recommendations on October 13, addressing migration challenges and vulnerable legacy coins.
Coinbase's paper urged developers to plan before quantum attacks become practical and called Bitcoin's eventual transition a multiyear effort. Its recommendations include examining BIP-360, which changes how certain Bitcoin transactions reveal keys, and wallets that could support existing and newer signature methods during a transition.
What is still unclear
- Researchers successfully transferred the remaining states between two error-correction methods, although larger tests are still needed.
- Coinbase cited limited block space, custody systems and dormant coins as unresolved problems, and owners who have lost access to their wallets may be unable to move funds when upgrades become available.
Questions readers ask
Did Google's quantum experiment break Bitcoin?
No. The experiment did not break Bitcoin's encryption. It reduced errors in a key quantum operation and produced states with 99.99% logical fidelity.
How many qubits would a quantum computer need to attack Bitcoin?
Google's earlier research estimated future cryptographic attacks could require fewer than 500,000 physical quantum qubits. In March, Google Quantum AI researchers gave the same figure under specified hardware assumptions.
How much Bitcoin has exposed public keys?
Glassnode estimated 6.04 million BTC had exposed public keys, representing 30.2% of mined Bitcoin. Blockonomi reported that about 6.9 million BTC may face exposure through already visible public keys.
What is Coinbase doing about quantum risk?
Coinbase published Bitcoin security recommendations on October 13, addressing migration challenges and vulnerable legacy coins. It urged developers to plan before quantum attacks become practical and called the transition a multiyear effort.
