Quantum Circuit Costs Plummet by 86% in Two Months

A recent challenge to optimize a component of a quantum attack on Bitcoin and Ethereum has produced a circuit significantly cheaper than previously reported. The benchmark, which measures the cost of a point-addition circuit for secp256k1, fell by 86% over two months, from 10.75 billion to about 1.496 billion. This is more than 50% below the result reported by Google Quantum AI in March.

The point-addition circuit is repeated many times inside Shor's algorithm, which a fault-tolerant quantum computer could use to recover a private key from a public key already exposed onchain. The authors stress that this is not an attack, but rather a way to shrink the margin holders are working with. According to Coinbase's quantum advisory board, roughly 7 million BTC sit in addresses with visible public keys.

The challenge was driven by over 100 researchers and AI agents, who worked together to optimize the circuit. The result was a point-addition circuit that needs 1,151 logical qubits and about 1.30 million Toffoli gates. While this is a significant improvement, one of the paper's authors cautioned against comparing it directly to Google's findings due to differences in interfaces and accounting conventions.