A coherence-witnessing game and applications to semi-device-independent quantum key distribution

Semi-device-independent quantum key distribution aims to achieve a balance between the highest level of security, device independence, and experimental feasibility. Semi-quantum key distribu-tion presents an intriguing approach that seeks to minimize users' reliance on quan-tum operations while maintaining secu-rity, thus enabling the development of sim-plified and hardware fault-tolerant quan-tum protocols. In this work, we in-troduce a coherence-based, semi-device-independent, semi-quantum key distribu-tion protocol built upon a noise-robust version of a coherence equality game that witnesses various types of coherence. Se-curity is proven in the bounded quantum storage model, requiring users to imple-ment only classical operations, specifically fixed-basis detections.