Google Quantum AI published a paper saying quantum attacks on Bitcoin and Ethereum may need far fewer qubits than prior estimates. The team described attack methods requiring ~1,200–1,450 high-quality qubits and outlined a practical real-time attack that precomputes work and can derive a private key from a revealed public key in ~9 minutes (~41% chance before a typical ~10-minute Bitcoin confirmation). Taproot’s default visibility of public keys increases exposure—Google estimates ~6.9 million BTC (≈one-third of supply) are in wallets with revealed public keys—while Ethereum is likely less exposed due to faster confirmations. Google shared results via a zero-knowledge proof and warned practical quantum timelines may be shorter than commonly assumed.

Google’s whitepaper quantifies lower qubit requirements (~1,200–1,450 high-quality qubits) and describes a concrete real-time attack that can recover a private key in ~9 minutes with ~41% chance before a typical Bitcoin confirmation; Taproot’s default public-key visibility means an estimated ~6.9M BTC are exposed; Google also used a zero-knowledge proof to publish findings and cautioned the timeline for practical quantum threats may be shorter. These are specific, concrete facts from the summary supporting negative sentiment and meaningful market impact.