We report on an experiment that demonstrates the violation of a Leggett-Garg inequality (LGI) with neutrons. LGIs have been proposed in order to assess how far the predictions of quantum mechanics defy macroscopic realism. With LGIs, correlations of measurements performed on a single system at different times are described. The measured value of K = 1.120 +/- 0.007, obtained in a neutron interferometric experiment, is clearly above the limit K = 1 predicted by macro-realistic theories.
@article{arxiv.2307.04409,
title = {Violation of a Leggett-Garg inequality using ideal negative measurements in neutron interferometry},
author = {Elisabeth Kreuzgruber and Richard Wagner and Niels Geerits and Hartmut Lemmel and Stephan Sponar},
journal= {arXiv preprint arXiv:2307.04409},
year = {2024}
}