# Underground test of quantum mechanics - the VIP2 experiment

## TL;DR

The VIP2 experiment at Gran Sasso tests the Pauli Exclusion Principle for electrons with unprecedented precision, searching for tiny violations through anomalous X-ray transitions, and explores potential collapse of the wave function.

## Contribution

This paper introduces the new VIP2 experimental setup designed to test PEP violations with sensitivity down to 10$^{-31}$, advancing the precision of quantum mechanics tests.

## Key findings

- Preliminary results obtained from the VIP2 experiment.
- The setup achieves unprecedented sensitivity in testing PEP violations.
- Discussion of implications if PEP violation is observed.

## Abstract

We are experimentally investigating possible violations of standard quantum mechanics predictions in the Gran Sasso underground laboratory in Italy. We test with high precision the Pauli Exclusion Principle and the collapse of the wave function (collapse models). We present our method of searching for possible small violations of the Pauli Exclusion Principle (PEP) for electrons, through the search for anomalous X-ray transitions in copper atoms, produced by fresh electrons (brought inside the copper bar by circulating current) which can have the probability to undergo Pauli-forbidden transition to the 1 s level already occupied by two electrons and we describe the VIP2 (VIolation of PEP) experiment under data taking at the Gran Sasso underground laboratories. In this paper the new VIP2 setup installed in the Gran Sasso underground laboratory will be presented. The goal of VIP2 is to test the PEP for electrons with unprecedented accuracy, down to a limit in the probability that PEP is violated at the level of 10$^{-31}$. We show preliminary experimental results and discuss implications of a possible violation.