Quantum coherence in neutrino oscillation in matter

TL;DR

This paper investigates how matter density affects quantum coherence in neutrino oscillations, revealing that coherence generally decreases in matter but can be infinite at specific densities, impacting our understanding of quantum mechanics and neutrino physics.

Contribution

It introduces a detailed analysis of decoherence in neutrino oscillations considering matter effects using the $l_1$-norm to quantify coherence, highlighting conditions where coherence is enhanced or infinite.

Findings

Coherence in matter is generally less than in vacuum.

Certain matter densities lead to infinite localization coherence lengths.

The $l_1$-norm effectively quantifies coherence dependence on matter density.

Abstract

A closer and more detailed study of neutrino oscillation, in addition to assisting us in founding physics beyond the standard model, can potentially be used to understand the fundamental aspects of quantum mechanics. In particular, we know that the neutrino oscillation occurs because the quantum states of the produced and detected neutrinos are a coherent superposition of the mass eigenstates, and this coherency is maintained during the propagation due to the small mass difference of neutrinos. In this paper, we consider the decoherence due to the neutrino interaction in the material medium with constant density in addition to the decoherence coming from the localization properties. For this purpose, we use $l_1\text{-norm}$ in order to quantify the coherence and investigate its dependence on the matter density. According to our results, in general, the coherence in material medium is less than vacuum. However, there exist exceptions; for some matter densities, the localization coherence lengths become infinite. So, for these cases, $l_1\text{-norm}$ in matter is more than the vacuum.