Alfonso Vázquez Ramallo

Neutrinos as Open Quantum Systems

Titor: Gonzalo Alonso Álvarez

Supervisor: Gonzalo Alonso Álvarez

Neutrino oscillations provide a natural setting in which to explore how quantum coherence evolves in realistic physical environments. The coherent evolution of neutrino states can persist over macroscopic distances, from terrestrial experiments to astrophysical baselines, making neutrinos an exceptional probe of decoherence and environmental effects. 

In the standard description, neutrinos are treated as isolated quantum systems whose flavour evolution is governed by the Schrödinger equation. In many realistic situations, however, particles propagate through complex environments that can induce decoherence and dissipation, requiring a more general framework based on the theory of open quantum systems.

In this project, the student will learn the density-matrix formalism and apply it to neutrino oscillations. Starting from the standard two-flavour framework, the student will study how environmental effects modify flavour evolution and oscillation probabilities. Applications will be discussed in particle physics and astrophysical settings, such as neutrino propagation in matter and in dense or early-Universe environments.

The project combines analytical calculations with simple numerical simulations and provides an introduction to modern techniques in quantum theory and their use in fundamental physics. Depending on progress and interest, the methods developed may also be applied to other oscillation phenomena, such as photon–dark-photon or photon–axion mixing, relevant to searches for physics beyond the Standard Model.