András Pályi

In distributed computing, a Byzantine fault is a condition where a component behaves inconsistently, showing different symptoms to different components of the system. Consensus among the correct components can be reached by appropriately crafted communication protocols, even in the presence of byzantine faults. Quantum-aided protocols built upon distributed entangled quantum states are worth considering, as they are more resilient than traditional ones. Based on earlier ideas, here we introduce a parameter-dependent family of quantum-aided weak broadcast protocols, and prove their security. We analyze the resource requirements as functions of the protocol parameters, and locate the parameter range where these requirements are minimal. Hence, our work illustrates the engineering aspects of future deployments of such protocols in practice. Following earlier work demonstrating the suitability of noisy intermediate-scale quantum (NISQ) devices for the study of quantum networks, we show how to prepare our resource quantum state on publicly available IBM quantum computers. We outline follow-up tasks toward practical quantum-aided byzantine fault tolerance.