Neutrino Oscillations and Quantum Information Theory

This undergraduate thesis investigates neutrino oscillations through both the conventional particle-physics framework and the modern lens of quantum information theory. It begins by developing the theoretical foundations of two- and three-flavor neutrino oscillations, emphasizing the role of the PMNS mixing matrix, mass-squared differences, and the CP-violating phase. The work provides a detailed analytical treatment of oscillation probabilities in vacuum and matter, clarifying why CP violation is only possible in the three-flavor framework. A key contribution of the thesis is the reinterpretation of neutrino flavor oscillations as a quantum entanglement phenomenon. By modeling flavor states as quantum subsystems, the study quantifies flavor-mode entanglement using von Neumann entropy and examines how coherence and mixedness arise from unitary evolution rather than decoherence. The behavior of entanglement entropy is analyzed both in vacuum and in matter, revealing how matter effects modify quantum correlations during propagation. The thesis also includes a computational analysis using Python, where three-flavor oscillation probabilities are numerically evaluated for multiple values of the CP-violating phase. The results demonstrate how CP violation alters oscillation amplitudes, phases, and flavor asymmetries, and how these effects correlate with changes in quantum entanglement measures. Overall, the work bridges neutrino physics and quantum information theory, offering physical insight into flavor oscillations as a manifestation of quantum correlations and highlighting the fundamental role of CP violation in neutrino dynamics.