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Abstract

This thesis explores how neutrinos may serve as a portal to effects in the quantum regime. Due to the smallness of neutrino masses and its feebly interacting feature, the neutrino system acts as a closed quantum system at a macroscopic scale. Nonetheless, as the precision of neutrino oscillation experiments increases, a closed quantum system description would become insufficient at some point, and a door to effects in the quantum regime through decoherence signatures would be open up. In order to sift the fundamental, quantum signal from the classical noise in the future detection, a more consistent machinery warrants development. For this purpose, we incorporate the concept of open quantum systems into the quantum field theory description of neutrino oscillations. As a result, we present a generic structure (introduced as the layer structure) for decoherence effects in neutrino oscillations, showing how decoherence signatures from quantum effects and classical uncertainties may be interpreted as phase wash-out effects on different layers with different phase structures. On the other hand, additional coherence could come into play when interactions with a low momentum transfer are included. In addition, we explore the expanded coherence due to the interaction with magnetic field, which flips the chirality of the neutrino through the theoretically motivated magnetic moment effect. For high energy neutrinos, such effect can be sizeable as some of them are likely to be produced in a highly magnetized region. By adopting a simple model aiming to investigate the imprints of magnetic moment effect on the neutrino flux generated from the particle collisions nearby a magnetar, possible signatures with the IceCube observatory is speculated and discussed.