Quantum Fisher Information as a Probe of Sterile Neutrino New Physics:Geometric Advantage of KM3NeT over IceCube

TL;DR

This paper uses Quantum Fisher Information to compare the sensitivity of KM3NeT and IceCube in detecting sterile neutrino physics, showing KM3NeT's geometric advantage and quantum-limited measurement potential.

Contribution

It introduces a quantum information framework to quantify and compare the fundamental sensitivity limits of neutrino detectors for sterile neutrino searches.

Findings

KM3NeT exceeds IceCube's information by three orders of magnitude for matter-induced scenarios.

IceCube needs over thirty times more events to match KM3NeT's precision.

A baseline of 150-200 km optimizes KM3NeT's sensitivity for sterile neutrino detection.

Abstract

We investigate a reported discrepancy between a high-energy neutrino detection at KM3NeT and its non-observation at IceCube, which suggests a statistical tension of up to 3.5 standard deviations. This gap has been proposed to arise from sterile neutrino oscillations over the 147-kilometer path to KM3NeT, driven by either matter-induced resonances or nonstandard interactions. Using the Quantum Fisher Information framework, we quantify the sensitivity of the neutrino state to these new physics couplings and establish fundamental precision limits via the quantum Cramer-Rao bound. Our analysis shows that the information available at KM3NeT exceeds that at IceCube by three orders of magnitude for matter-induced scenarios. We demonstrate that IceCube would require over thirty times more events to match the precision of a single KM3NeT detection. We identify an optimal baseline of 150 to 200 kilometers, placing KM3NeT in a superior position for these measurements. Our results show that standard detection methods already reach the ultimate quantum precision limit, and that a small number of future events at KM3NeT could provide the first quantum-limited constraints on sterile neutrino couplings.