Google and Quantinuum announce quantum error correction breakthroughs raising Bitcoin security questions
Google's Willow chip cut magic-state errors 40-fold while Quantinuum hit 99.9995% logical fidelity, both advancing fault-tolerant quantum computing timelines.
Why it matters
Progress in quantum error correction shortens the theoretical timeline for machines capable of breaking elliptic-curve cryptography, increasing urgency for Bitcoin's quantum-resistant upgrade planning. The signature size trade-off poses consensus and block-space challenges for any future migration.
Where the sources disagree
Quantum error correction metrics and claims
40-fold magic-state error reduction, 99.99% fidelity, 8% success rate
Crypto News Flash, CoinDesk
99.9995% logical fidelity, tenfold improvement, 100x better than competing architectures
Bitcoin.com News, Crypto News (CryptoNews.net)
Google reports a 40-fold reduction in magic-state preparation errors with 99.99% fidelity but 8% success rate, while Quantinuum reports 99.9995% logical fidelity, a tenfold improvement from September, and claims 100x better than competing architectures; the metrics measure different aspects of quantum error correction and are not directly comparable.
Key facts
Google's Willow chip reduced magic-state preparation errors by approximately 40 times
40 timesDisputed figureReported by Crypto News Flash
Willow achieved 99.99% fidelity among magic states that passed inspection
99.99 %Disputed figureReported by Crypto News Flash
Only about 8% of Willow's magic-state preparation attempts succeeded
8 %Disputed figureReported by Crypto News Flash
Google's Willow result was published in Science on October 15
Reported by Crypto News Flash
An illustrative ML-DSA-44 signature and public key would require 3,732 bytes versus 64 bytes for a Schnorr signature
3,732 bytesReported by Crypto News Flash
The ML-DSA-44 replacement is roughly 58 times larger than the current signature payload
58 timesReported by Crypto News Flash
Under current SegWit weight rules the replacement could add 917 virtual bytes per spend
917 virtual bytesReported by Crypto News Flash
A modeled quantum attack on Bitcoin would require roughly 500,000 reliable magic states per second
500,000 magic states per secondReported by CoinDesk
What happened
Google reported its Willow processor reduced magic-state preparation errors by roughly 40 times, achieving 99.99% fidelity though only 8% of attempts succeeded, per a Science publication on October 15. Separately, Quantinuum announced its Helios system reached 99.9995% logical fidelity, a tenfold improvement from September, targeting a fault-tolerant computer by 2029. Both advances relate to quantum capabilities that could eventually threaten Bitcoin's cryptographic signatures, though neither demonstrates an actual attack. Researchers note fitting post-quantum signatures like ML-DSA-44 into Bitcoin's block space would require roughly 58 times more bytes than current Schnorr signatures.
How the story developed
- Update
Google publishes Willow quantum error correction result in Science
Google reports 40-fold reduction in magic-state preparation errors achieving 99.99% fidelity
- First report
First report by Crypto News Flash
Google’s Quantum Advance Exposes Bitcoin’s Hidden Upgrade Cost
- Update
Crypto News Flash covers Google Willow breakthrough
Details signature size implications for Bitcoin post-quantum migration
- Independent corroboration
Independently corroborated by CoinDesk
Satoshi-era bitcoin faces a bigger quantum threat after Google’s new Willow breakthrough
- Update
CoinDesk reports on Google Willow and Bitcoin quantum threat
Adds context on modeled attack requiring 500,000 magic states per second
- Official statement
Official statement from Bitcoin.com News
Smashed Quantum Computing Record Raises Stakes for Bitcoin Security
- Official statement
Quantinuum announces Helios logical fidelity record
Achieves 99.9995% logical fidelity, tenfold improvement targeting 2029 fault-tolerant computer
- Update
Crypto News covers Quantinuum breakthrough with independent expert comment
Includes Sandia Labs assessment on physical qubit requirements for scaled systems
How coverage built up
Independent sources over time, counted the way the consensus panel counts them: a republication of a wire story does not move the line.
- 16 Oct 2026, 07:50 UTC: Crypto News Flash — 1 independent source, 1 reports
- 17 Oct 2026, 02:30 UTC: CoinDesk — 2 independent sources, 2 reports
- 19 Oct 2026, 21:55 UTC: Bitcoin.com News, official — 3 independent sources, 3 reports
Affected entities
Original sources
| Publisher | Report | Role | Published |
|---|---|---|---|
| Bitcoin.com News Company, official | Smashed Quantum Computing Record Raises Stakes for Bitcoin Security | Independent | |
| Crypto News Flash Crypto media | Google’s Quantum Advance Exposes Bitcoin’s Hidden Upgrade Cost | Original | |
| CoinDesk Crypto media | Satoshi-era bitcoin faces a bigger quantum threat after Google’s new Willow breakthrough | Independent | |
| Crypto News (CryptoNews.net) Aggregator | Smashed Quantum Computing Record Raises Stakes for Bitcoin Security | Syndicated |
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