Resource analysis for quantum-aided Byzantine agreement with the four-qubit singlet state

TL;DR

This paper analyzes the resource requirements for quantum-aided Byzantine agreement protocols using four-qubit singlet states, demonstrating their feasibility on current quantum computers and highlighting engineering considerations.

Contribution

It introduces a parameter-dependent family of quantum protocols, computes failure bounds, and experimentally implements the resource state on NISQ devices.

Findings

Upper bounds on failure probability established

Resource minimization procedure illustrated

Quantum state created on real quantum computers

Abstract

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 establish a parameter-dependent family of quantum-aided weak broadcast protocols. We compute upper bounds on the failure probability of the protocol, and define and illustrate a procedure that minimizes the quantum resource requirements. Following earlier work demonstrating the suitability of noisy intermediate scale quantum (NISQ) devices for the study of quantum networks, we experimentally create our resource quantum state on publicly available quantum computers. Our work highlights important engineering aspects of the future deployment of quantum communication protocols with multi-qubit entangled states.