The predictable failure of the QDay Prize

Craig Gidney, a quantum computing researcher, explains why he predicted the QDay Prize — a competition awarding 1 bitcoin for the largest problem solved using Shor's algorithm on current quantum hardware — would fail, and why it did. Two fundamental flaws doomed it: current quantum computers lack error correction needed for cryptographically relevant Shor's algorithm runs, and small-scale problems can be solved by luck rather than genuine quantum computation. The winning submission turned out to be a 'Falling With Style' trick — its quantum circuit produced results indistinguishable from random number generation, meaning the quantum computer contributed nothing. Gidney criticizes competition organizers (Project11) for awarding the prize anyway and for framing it as a 512x progress jump, arguing the result would have been identical if run in 1996. He warns this outcome will likely undermine legitimate post-quantum cryptography awareness efforts rather than advance them.