Quantum Computers Could Crack Bitcoin Far Sooner Than Expected, Caltech Finds

A team from Caltech and startup Oratomic has shown that a quantum computer capable of running Shor’s algorithm — the protocol that breaks modern encryption — could work with just 10,000 qubits. Previous estimates put that number at one million or higher. The finding, published March 31, dramatically compresses the timeline for when quantum machines could threaten blockchain cryptography.

The result dismantles the core argument that quantum threats to Bitcoin remain decades away.

The Defense That No Longer Holds

Until now, quantum skeptics relied on a straightforward calculation. Breaking Bitcoin’s elliptic curve cryptography requires roughly 2,100 logical qubits. Each logical qubit needs up to 10,000 physical qubits for error correction. That puts the total hardware requirement at around 21 million physical qubits. With today’s best machines running about 6,000 noisy qubits, critics like Bitcoin entrepreneur Ben Sigman argued the real threat was 30 to 50 years away.

The Caltech team’s new error-correction architecture changes that math entirely. Their approach exploits neutral atoms’ unique ability to move physically across qubit arrays using laser-based optical tweezers. This enables long-range entanglement and high-rate error-correction codes. The result cuts the physical-to-logical qubit ratio from roughly 1,000-to-1 down to approximately 5-to-1.

Apply that ratio to the same 2,100 logical qubits. The total drops to around 10,500 physical qubits. That is less than double the 6,100-atom array that Caltech professor Manuel Endres already built in his lab.

John Preskill, Caltech’s Feynman Professor of Theoretical Physics, has worked on fault tolerance longer than some of his coauthors have been alive. He said the field is finally getting close to its goal.

6.7 Million BTC Already Mapped as Targets

The timing makes the finding harder to dismiss. Just one day earlier, on March 30, Google Quantum AI published a whitepaper mapping Bitcoin’s quantum attack surface for the first time. The research identified approximately 6.7 million BTC sitting in addresses vulnerable to so-called at-rest attacks. These include Pay-to-Public-Key addresses from Bitcoin’s earliest mining era, in which public keys are permanently exposed on the blockchain.

A quantum computer running Shor’s algorithm could derive private keys from those exposed public keys and drain the funds. Around 1.7 million BTC are locked in P2PK scripts alone. Many are held in dormant wallets, including coins widely attributed to Satoshi Nakamoto. As Deloitte’s analysis has noted, these addresses cannot be upgraded or migrated to post-quantum cryptography.

The Bottleneck Is Governance, Not Code

CryptoQuant CEO Ki Young Ju has argued that the hardest part of a quantum upgrade is not technical. Reaching consensus within the Bitcoin community on what to do with vulnerable coins — especially freezing Satoshi’s estimated one million BTC — could prove far more difficult than writing new code.

The block size debate lasted over three years and produced hard forks. A proposal to freeze dormant coins would face similar or greater resistance. Ju warned that full agreement may never materialize, raising the possibility of competing Bitcoin forks as quantum hardware advances.

The Caltech paper does not solve that governance problem. But it does remove the comfortable assumption that the community has decades to figure it out. The researchers have founded Oratomic to commercialize their architecture and aim to build utility-scale fault-tolerant quantum computers before the decade ends.