CRQC (Cryptographically Relevant Quantum Computer)

A cryptographically relevant quantum computer is a hypothetical machine powerful enough to break the public-key cryptography that secures modern finance and communications. Published research generally places the requirement in the low thousands of error-corrected logical qubits, which could demand millions of physical qubits, while the largest devices demonstrated publicly by 2026 held on the order of a thousand physical qubits.

Why it matters

The distance between today's hardware and a CRQC is measured in error correction, not raw qubit count. Physical qubits are noisy, and hundreds to thousands may be needed to sustain one reliable logical qubit. Governments are not waiting: US agencies have been directed to migrate to post-quantum cryptography, with federal targets extending to 2035, partly because encrypted data harvested today could be decrypted by a future CRQC.

For bitcoin, a CRQC running Shor's algorithm could derive private keys from exposed public keys, threatening coins held in early pay-to-public-key outputs and in reused addresses.

In the gold vs bitcoin debate

Quantum risk is a genuinely asymmetric argument in the gold vs bitcoin comparison. A CRQC cannot do anything to a bar of gold, while bitcoin would need a coordinated protocol migration. Bitcoin defenders respond that the same machine would break banking, government, and internet security first, and that bitcoin can upgrade its signatures while gold cannot upgrade anything.