Security
Alice & Bob estimates 22,593 physical cat qubits could run Shor's algorithm on RSA-2048
Alice & Bob researchers estimate that Shor's algorithm against RSA-2048 would need 22,593 physical cat qubits and 3.14 days on fault-tolerant superconducting hardware. For the 256-bit elliptic-curve discrete logarithm problem, the estimate is 29,588 physical qubits and 61.8 minutes. Alice & Bob says its figure is 40 times fewer physical qubits than Google Quantum AI's Craig Gidney 2025 estimate, and says LDPC-cat codes cut its earlier 2023 estimate from 49,649 to 22,593 physical qubits. The paper, posted on IACR ePrint, also uses a redesigned adder and chip layouts and schedules for the most resource-heavy parts of the algorithm; the article does not say it has been peer reviewed.
Why it mattersThese are theoretical resource projections, not demonstrations of an attack, and the company says substantial engineering challenges remain. Alice & Bob expects hardware progress and falling requirements to converge in the early 2030s, and notes that US and UK guidance calls for completing the move to post-quantum cryptography by 2035.