Physicists have searched for deviations from standard quantum mechanics, testing whether quantum mechanics requires a more complex set of mathematical rules. To do so a research team led by Philip Walther at the University of Vienna designed a new photonic experiment using exotic metamaterials, which were fabricated at the University of California Berkeley. Their experiment supports standard quantum mechanics and allows the scientists to place bounds on alternative quantum theories. The results, which are published in Nature Communications, could help to guide theoretical work in a search for a more general version of quantum mechanics.