Quantum coherence in neutrino spin-flavor oscillations

TL;DR

This paper explores quantum coherence in neutrino spin-flavor oscillations, revealing that coherence can persist over astrophysical distances, which is a significant extension from previous studies focused on flavor oscillations.

Contribution

It introduces the analysis of quantum coherence in neutrino spin-flavor oscillations within magnetic fields, extending the understanding of coherence over much larger, astrophysical scales.

Findings

Coherence in flavor oscillations remains high over kilometers relevant for terrestrial experiments.

In spin-flavor oscillations, coherence can extend from kiloparsecs to gigaparsecs, covering astrophysical distances.

Quantum coherence measures are expressed in terms of oscillation probabilities, linking theory with observable quantities.

Abstract

Coherence, which represents the superposition of orthogonal states, is a fundamental concept in quantum mechanics and can also be precisely defined within quantum resource theory. Thus exploring quantum coherence in neutrino oscillations can not only help in examining the intrinsic quantum nature but can also explore their potential applications in quantum information technologies. Previous studies on quantum coherence have focused on neutrino flavor oscillations (FO). However, FO imply that neutrinos have mass and this can lead to the generation of a tiny but finite magnetic dipole moment of neutrinos through quantum loop diagrams at higher orders of perturbative expansion of the interaction. This electromagnetic property of neutrinos can induce spin flavor oscillations (SFO) in the presence of an external magnetic field and hence is expected to enrich the study of coherence. In this work, we investigate quantum coherence in neutrino SFO with three flavor mixing within the interstellar as well as intergalactic magnetic fields, quantified by the $l_1$ norm and the relative entropy of coherence, and express these measures in terms of neutrino SFO probabilities. For FO, coherence measures can sustain higher values (say, within 50% of the maximum) over distances of several kilometers, which are relevant for terrestrial experiments like reactor and accelerator neutrinos. However, for SFO, we find that the coherence scale can extend to astrophysical distances, spanning from kiloparsecs to gigaparsecs.