Of the approximately 20 million Bitcoins in circulation, just over 10,000 are actually stored in wallets that are exposed to quantum attacks.
The figure comes from crypto asset management firm CoinShares, which discovered in February that only 10,230 coins were vulnerable to quantum computing and associated with wallet addresses with publicly available cryptographic keys.
In today’s prices, this equates to nearly $730 million. The company said the amount resembled a routine transaction rather than a market crisis.
Steel frame takes shape in Chicago
The discovery came at an awkward moment. This week, PsiQuantum co-founder Peter Shadbolt posted a photo to X showing a construction site in Chicago where his company is building what he calls the world’s first commercially useful quantum computer.
Workers assembled 500 tons of steel in six days. The structure will house a machine capable of running one million qubits, a unit of quantum computing power.
Scientists say this capacity is theoretically enough to crack the encryption that protects Bitcoin wallets.
It’s time to build a really big quantum computer. 500 tons of steel increased in 6 days. Cryoplant delivery deadlines are strangling us. Thank you to the hundreds of people who are bound to this mission pic.twitter.com/eqSwsESusK
— Pete Shadbolt (@PeteShadbolt) March 5, 2026
The company announced in September that it had raised $1 billion for the project, with chipmaker Nvidia as a key partner.
PsiQuantum says the facility is designed to support fault-tolerant quantum computing and serve as the infrastructure for next-generation AI systems.
For comparison, the largest quantum computer currently operating at Caltech runs on 6,100 qubits. The jump to 1 million people represents an unprecedented scale in this sector.
What is actually at risk?
Bitcoin encryption relies on a 256-bit cryptographic key. A preprint paper published last month suggests that about 100,000 qubits are needed to crack a 2048-bit key, and mathematics suggests that a million-qubit machine could do the job.
But experts have long pointed out that the number of raw qubits is only part of the equation. Error rates and system stability are equally important.
BTCUSD trading at $68,470 on the 24-hour chart: TradingView
Not all Bitcoin wallets are equally at risk. Coins held in addresses that have never transacted (known as unspent transaction outputs or UTXOs) are considered to be most at risk, especially those whose public keys are exposed on the blockchain. Many of these wallets date back to the early days of Bitcoin.
Developers are already working on a fix
Bitcoin developers have been debating how to respond. One option being considered is a hard fork (a fundamental change to the network code) to introduce post-quantum cryptography.
The co-authors of BIP-360, a proposal aimed at making Bitcoin quantum-proof, said the upgrade could take up to seven years to be fully implemented.
PsiQuantum said it does not intend to use its technology to attack Bitcoin. Co-founder Terry Rudolph made this point publicly at the Bitcoin Quantum Summit last July.
Experts in the field say a full-fledged quantum threat to Bitcoin is at least a decade away.
For now, construction continues in Chicago, adding 500 tons of steel.
Featured image from Unsplash+/Alex Shuper, chart from TradingView
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