Fidelity-Aware Entanglement Routing and Failure-Resilience Analysis in Multi-Hop Quantum Repeater Networks using an Interactive Software Simulation Laboratory

Quantum repeater networks are a potential foundation for long-distance quantum communication, but entanglement routing is complicated by probabilistic link generation, imperfect entanglement swapping, fidelity degradation, limited resources, and component failures. This paper presents an interactive software simulation laboratory for investigating fidelity-aware routing and failure resilience in multi-hop quantum repeater networks. The framework represents repeaters and communication links as a graph and supports eight topology families: ring, star, linear chain, grid, mesh, random, small-world, and scale-free. A configurable weighted-score heuristic evaluates feasible routes using modelled end-to-end fidelity, estimated request success probability, residual capacity, path latency, and link utilisation. The laboratory also incorporates abstract entanglement-generation and swapping operations, configurable link and repeater failures, network visualisation, performance monitoring, and CSV-based data export. Its graph-based visualisation is intended to support structural interpretation and does not represent a trained graph neural network or learned routing policy. The mathematical model and documented simulation configuration establish a basis for reproducible experiments; however, quantitative comparisons are required to determine the effectiveness of the routing heuristic under different network conditions. Accordingly, this work focuses on the design and capabilities of an exploratory simulation environment rather than claiming demonstrated superiority over existing routing algorithms or quantum-network simulators.