A Comparative Study between Three Encryption Systems in a Quantum Computer (BB84, B92, BBM92) in Free Space Communication

Abstract

This research explores the fundamental principles of quantum computing and their application in enhancing communication security through Quantum Key Distribution (QKD) in free-space channels. Classical cryptographic methods face inherent limitations, particularly with the advent of quantum computational capabilities. Quantum mechanics, specifically the principles of superposition and entanglement, offers a robust framework for secure communication, ensuring that any attempt at eavesdropping inevitably perturbs the quantum state, thus revealing the intruder's presence. Through comprehensive simulations, this study analyzes the performance of QKD systems in free-space communication. Key parameters such as transmittance efficiency ( ), Quantum Bit Error Rate (QBER), and Secret Key Rate (SKR) are evaluated. Results indicate that transmittance efficiency in free space generally decreases with increasing zenith angle, with downlink scenarios (day and night) exhibiting higher efficiencies compared to uplink during the night. For all protocols, simulations demonstrate an increase in QBER and a corresponding decrease in SKR as the zenith angle increases, with downlink performance consistently surpassing uplink in terms of a higher SKR and a lower QBER