From Bell’s Theorem to Quantum Key Distribution: Mapping the Fundamental Assumptions

Abstract

Bell inequality violations play a central role in Bell-based and device-independent quantum key distribution (DI-QKD). In this work, we review fundamental assumptions and operational conditions at the theoretical, experimental, and cryptographic levels, including locality, measurement independence, single outcomes, experimental loopholes, trusted randomness, laboratory isolation, and adversarial constraints. We further examine the relationships between these assumptions across the theoretical, experimental, and cryptographic levels. We also clarify common misconceptions concerning determinism, realism, and hidden variables. This analysis provides a structured framework for understanding the role of assumptions in Bell’s theorem, Bell experiments, and Bell-based quantum cryptography.