Google researcher estimates RSA-2048 could be factored with under a million noisy qubits

Google Quantum AI/Willow and error-correction roadmap

Craig Gidney of Google Quantum AI estimated that a 2048-bit RSA key could be factored in under a week with fewer than a million noisy qubits, about 20 times fewer than his 2019 estimate. The result incorporates recent algorithmic advances and fault-tolerance techniques, tightening the timeline for post-quantum cryptography adoption.

• Under 1M noisy qubits could factor RSA-2048 in under a week; 2019 estimate required ~20M qubits over 8 hours.
• Assumes square qubit grid, nearest-neighbor connections, 0.1% error rate, 1 microsecond surface-code cycle time.
• Progress reflects algorithmic improvements (Ekerå-Håstad period finding) and efficient fault-tolerance (yoked surface codes, magic state cultivation).