Google’s Willow Chip Cuts Quantum Errors 40-Fold, Raising Questions for Old Bitcoin

Google says its Willow quantum chip prepared special “magic states” with about 40 times fewer errors, according to a study published in Science this week. These states act like single-use fuel for advanced quantum calculations, so making them cheaply removes one hardware bottleneck on the road to a machine that could crack bitcoin wallets. The debate usually centers on machine size, while the preparation workload gets less attention. Google reported roughly 99.99% fidelity, but only about 8 of every 100 attempts passed inspection. Larger scale tests and real-time operation are still ahead.

Why Satoshi-Era Coins Are Exposed

A wallet’s public key can be worked backward into its secret key by a big enough quantum computer running Shor’s algorithm, a method published in 1994 and never yet demonstrated. Some of the oldest coins have shown their public keys since they were mined, so a future attacker would have unlimited time. Newer formats hide the key behind a hash until the owner spends, which leaves a much tighter window. Lost coins are the hardest case, since owners with missing keys cannot move them to stronger protection. On Oct. 7, 100.02 BTC dormant since July 2010 moved, worth about $8.5 million, and in August six wallets idle since 2011 to 2014 shifted 553.59 BTC. Those moves do not prove quantum worries are the reason.

How This Fits With Earlier Research

Google estimated in March that a superconducting machine with fewer than 500,000 physical qubits could break Bitcoin and Ethereum cryptography, and that estimate already assumed efficient magic state production. So the new result tests part of that approach rather than adding another 40-fold cut. That paper modeled a nine minute attack needing about 500,000 reliable magic states every second.