BANDAL 🐻🎒

Today we are releasing Quantum Cadence, a post-quantum version of Cadence, our consensus protocol with multiple concurrent proposers. Quantum Cadence uses no quorum certificates, and its safety and liveness do not depend on signatures. Most modern consensus protocols, Cadence included, rely heavily on signatures and quorum certificates, which a large-scale quantum computer could forge. Simply replacing today's signatures with post-quantum ones would make certificates too large for every validator to send around in a high-performance blockchain. Quantum Cadence instead draws on Forget-IT, a recent signature-free consensus protocol co-developed by researchers at Category Labs. Quantum Cadence still keeps the overall architecture and core guarantees of Cadence, so our Cadence prototype was easy to carry over: an AI was able to adapt it to Quantum Cadence in a few hours, and an early prototype now runs on an internal test network. We designed Quantum Cadence to be practical for a high-performance blockchain. In our simulations, its latency is similar to Cadence's, and it scales better with the number of proposers. Interactive explainer: category.xyz/quantum-cadence. Full paper: arxiv.org/abs/2610.32803. Joint work by @MohammadMJalal1, @TobiasKlenze, and @komasito55