Google reported approximately 99.99% fidelity, a metric indicating how closely the final quantum states aligned with researchers’ targets.
That figure applies only to states that passed inspection. Willow retained roughly 8% of its attempts following preparation and measurement checks—about eight out of every 100 tries.
Next steps involve scaling the process significantly while preserving state integrity for use in extended calculations. Researchers note that additional work is required on real-time operations and integrating these states into more robust error-correction frameworks.
Context from Prior Research
In March, Google projected that a future superconducting quantum computer with fewer than 500,000 physical qubits could compromise the wallet cryptography securing Bitcoin and Ethereum, based on a defined set of hardware assumptions.
In September, CoinDesk covered research that reduced the computational workload for a core calculation central to that attack. That effort addressed a single component, omitting the full attack and the physical hardware costs of execution.
Those studies lower the mathematical burden on an attacker. Cultivation, meanwhile, addresses the expense of supplying the machine while it performs that work.
The improvements cannot simply be multiplied. Google’s March estimate already accounted for efficient magic-state production. This experiment evaluates part of that engineering approach rather than delivering another 40-fold reduction in the estimated cost of attacking Bitcoin.