# Direct probe of the interior of an electric pion in a Cooper pair superinsulator

## TL;DR

This paper demonstrates that superinsulating films can serve as a model system for hadron physics, providing direct experimental insights into quark-like behavior, confinement, and asymptotic freedom using Cooper pairs in NbTiN films.

## Contribution

It introduces superinsulating films as a novel platform to emulate hadron physics phenomena, including direct observation of confinement and asymptotic freedom.

## Key findings

- Evidence of asymptotic freedom in superinsulating films
- Observation of 't Hooft's dual superconductivity confinement mechanism
- Detection of magnetic monopoles in NbTiN films

## Abstract

The nature of hadrons is one of the most fundamental mysteries of physics. It is generally agreed that they are made of "colored" quarks, which move nearly free at short scales but are confined inside hadrons by strong interactions at large distances. Because of confinement, quarks are never directly observable and, experimentally, their properties can be tested only indirectly, via high energy collisions. Here we show that superinsulating films realize a complete, one-color model system of hadron physics with Cooper pairs playing the role of quarks. We report measurements on highly controlled NbTiN films that provide a window into the interior of "Cooper pair mesons" and present the first direct evidence of asymptotic freedom, `t Hooft's dual superconductivity confinement mechanism, and magnetic monopoles.