PsiQuantum has started construction on a facility designed to house a 1 million-qubit quantum computer, a scale researchers say could be powerful enough to break Bitcoin’s cryptography. Co-founder Peter Shadbolt posted a photo of the Chicago site showing 500 tons of steel erected in six days. The company announced in September it had raised $1 billion, in collaboration with Nvidia, to build a plant intended to host quantum machines that can operate despite errors and to support “next-generation AI supercomputers.”
The prospect has reignited concerns in the Bitcoin community that large-scale quantum computers could compromise cryptographic keys. Some warn the network, which secures trillions in value, could be at risk, while figures like Blockstream CEO Adam Back have argued quantum threats to Bitcoin are at least a decade away. Bitcoin developers are discussing whether immediate action—such as a hard fork to introduce quantum-resistant measures—is warranted.
Coins most exposed are UTXOs tied to addresses that have never spent funds and thus have publicly visible cryptographic keys; many date back to Bitcoin’s early years. Estimates for how many qubits are needed to break relevant keys vary and have fallen as research progresses. A recent preprint argued roughly 100,000 qubits might be required to break 2048-bit keys; Bitcoin uses 256-bit keys. By comparison, the largest quantum computer at Caltech currently has about 6,100 qubits.
PsiQuantum co-founder Terry Rudolph has said the company has no plans to use its machines to derive private keys from public keys. CoinShares research in February found that only about 10,230 BTC are both quantum-vulnerable and in addresses with exposed public keys—an amount that, if sold, would likely resemble routine market activity rather than destabilize the system.