MilestoneTheory & algorithmsClaimed

Alice & Bob estimates RSA-2048 could be broken with about 23,000 cat qubits

Oct 29, 2026

In a preprint, researchers at the French startup Alice & Bob and Inria estimate that Shor's algorithm could factor a 2048-bit RSA key with 22,593 physical cat qubits in about 3.14 days. It assumes cat qubits with almost no bit-flip errors, which today's hardware does not yet achieve.

Why it matters

It is the latest in a run of shrinking estimates for a code-breaking machine, down from millions of qubits a few years earlier, though it rests on theory and simulation, not experiments.

Alice & Bob

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