Google says its Willow quantum chip cut errors about 40-fold when preparing "magic states," a key ingredient quantum computers consume as they run, and CoinDesk reported on Oct. 16 that the result adds to concern about bitcoin's oldest coins. The result was published in Science the same week. What the report does not claim matters most: it asserts no current threat to bitcoin, does not say an attack is feasible now, and says the result does not make a bitcoin attack 40 times cheaper.
What Google reported
Google's method, called cultivation, creates a rough magic state, checks it for errors, and discards flawed attempts. Finished states showed about 99.99% fidelity, but only states that passed inspection counted, and about 8 of every 100 attempts succeeded. Next steps include larger-scale runs, keeping states useful in longer calculations, real-time operations, and moving states into stronger error-correcting setups. It's an experiment on one engineering component, per the article, and scaling challenges remain.
Why bitcoin's old coins are the focus
Shor's algorithm, first published in 1994, could in theory derive a secret key from a public key on a large enough quantum computer, and CoinDesk says no one has demonstrated this. The exposure comes from how bitcoin works: spending typically reveals the public key, and some payment types expose it from the start, while hashed formats hide it until the owner spends. Some of bitcoin's oldest holdings have had exposed public keys since they were mined. Where keys are lost, owners can't move old coins into stronger protections, and the exposed keys stay available to an attacker. The article gives no total amount of bitcoin at risk, so we don't either.
The resource estimates behind the worry
CoinDesk cites Google's March estimate that a future superconducting quantum computer with fewer than 500,000 physical qubits could break the wallet cryptography used by Bitcoin and Ethereum, under specific hardware assumptions. For one modeled attack lasting about nine minutes after a public key becomes available, Google estimated roughly 500,000 sufficiently reliable magic states per second would be needed. A September CoinDesk report covered researchers reducing the workload of one core calculation in that attack, though not the full attack or physical hardware costs. Crucially, CoinDesk says the new gains cannot simply be multiplied, because Google's March estimate already assumed efficient magic-state production.
Old coins that moved
The article notes two recent transfers of long-dormant bitcoin. On Oct. 7, 100.02 BTC untouched since July 2010, worth about $8.5 million, moved. In August, six wallets inactive since 2011–2014 moved 553.59 BTC, about $40 million at the time. CoinDesk is explicit that these moves do not by themselves show holders are reacting to quantum fears, and we agree: dormant coins move for many reasons, and nothing in the reporting ties these to quantum concerns.
How to read this story
The responsible reading is "a research milestone and a reason the bitcoin community discusses migration paths," not "bitcoin is about to break." The article quotes no outside quantum experts, and the caveats it reports come from the researchers themselves. A related worry surfaced in the Oct. 9 selloff coverage, when Ethereum researcher Justin Drake's warning that AI could break the math securing wallets sooner than expected was cited as one of several pressures; see our report on ether liquidations. CoinDesk's piece covers only bitcoin; for other networks' plans, check their own developer communications.
Fast answers
Can quantum computers break bitcoin today?
No. CoinDesk's report asserts no current threat to bitcoin and does not say an attack is feasible now. It notes no one has demonstrated Shor's algorithm deriving a key from a public key on a large enough quantum computer.
What did Google's Willow chip achieve?
Google says Willow cut errors about 40-fold when preparing magic states, with finished states at about 99.99% fidelity, though only states that passed inspection counted and about 8 of every 100 attempts succeeded. The result was published in Science.
Does the Willow result make attacking bitcoin 40 times cheaper?
No. CoinDesk says the gains cannot simply be multiplied, because Google's March estimate already assumed efficient magic-state production, and the experiment tests only one engineering component.
Why are old bitcoin coins considered more exposed?
Spending typically reveals a public key, and some payment types expose it from the start, so some of bitcoin's oldest holdings have had exposed public keys since they were mined. If keys are lost, owners can't move coins into stronger protections.
Sources: CoinDesk (Shaurya Malwa, Oct. 16, 2026), citing Google's Willow result published in Science and Google's March resource estimate.