Securing Elliptic Curve Cryptocurrencies against Quantum Vulnerabilities: Resource Estimates and Mitigations

A whitepaper from Google Quantum AI estimating the quantum resources required to solve the 256-bit elliptic-curve discrete logarithm problem (ECDLP-256) that secures bitcoin and similar systems. It reports markedly lower requirements than earlier work — on the order of ~1,200 logical qubits and fewer than 500,000 physical qubits — framed as roughly a 20× reduction versus prior estimates.

These are estimates for an idealized fault-tolerant machine, not a demonstration; hardware at that scale does not exist, and the figures depend on assumptions about error rates and architecture. Press coverage compressed the result into "break bitcoin in minutes," which conflates an asymptotic resource estimate with a working attack.

The paper also discusses mitigations and was published alongside a verifiable proof of its circuit simulation rather than the circuits themselves. It is one of the more concrete recent inputs to the timeline debate.