The question of whether quantum phenomena can be explained by classical models with hidden variables is the subject of a long-lasting debate. One feature of classical models that is thought to be in conflict with quantum mechanics is non-contextuality, with experiments undertaken with photons and neutrons seeming to support this. However, these tests required the generation of special quantum states and left various loopholes open. Here an experiment is performed with trapped ions that overcomes these problems and cannot be explained in non-contextual terms.
- G. Kirchmair
- F. Zähringer
- C. F. Roos
