Mhlambululi Mafu

As our lives and interactions become more dependent on the internet, our security needs continue to evolve. Future transactions will likely be secured by quantum means such as point-to-point quantum key distribution and more complex quantum protocols. Quantum key distribution has the potential to revolutionize secure communication, but it is often limited by device imperfections and environmental factors such as weather conditions. Currently, quantum key distribution schemes based on orbital angular momentum-carrying optical beams employ conventional settings. As a result, various attacks, such as detector side-channel attacks, are possible, and these beams are subject to spatial aberrations because of atmospheric turbulence and poor weather conditions. As a result, we present a novel approach to measurement device-independent quantum key distribution scheme using vortex vector modes and scalar beams that is capable of achieving high key rates even under diverse weather conditions, including clear skies, light rain, and fog. Furthermore, adopting this approach maximizes the advantages of both orbital angular momentum states and measurement device-independent quantum key distribution. According to our implementation, a secure key can be transmitted up to a maximum distance of approximately 178 kilometers under clear conditions, and we can transmit signals up to a comparable distance of approximately 160 kilometers under adverse weather conditions. Since these distances are comparable, this work presents a significant advance, illustrating how measurement device-independent quantum key distribution can be implemented using vortex vector modes. Most significantly, results demonstrate the effectiveness of this approach, opening up new possibilities for secure long-distance communication under adverse weather conditions.