# Macroscopic polarization entanglement and loophole-free Bell inequality test

## TL;DR

This paper demonstrates a feasible loophole-free Bell test using multi-photon polarization entanglement and linear optics, enabling exploration of quantum effects in macroscopic and biological systems.

## Contribution

It introduces a preselection protocol to generate genuine macroscopic superpositions and entanglement without postselection or dark counts.

## Key findings

- Loophole-free Bell test achievable with current technology
- Generation of macroscopic superpositions using polarization entanglement
- Potential applications in quantum biology and manipulation of living organisms

## Abstract

The question whether Quantum Mechanics describes all aspects of both the micro-world of elementary particles and living organisms adequately is still open. A Bell inequality test without locality and detection loopholes will deliver the answer when applied to macroscopic systems. Here we show that an experimentally feasible loophole-free Bell test is possible using only multi-photon polarization entanglement and linear optics. We apply a preselection protocol which produces genuine macroscopic superpositions and entanglement, thus eliminating postselection and dark counts. Such superpositions are usually difficult to generate. Their study paves the way for testing the quantum nature of biological organisms such as plants, viruses and human brain. Our results find application in creating quantum superpositions of living organisms and their manipulation.