Fundamentally binary theories are nonsignaling theories in which measurements of many outcomes are constructed by selecting from binary measurements. They constitute a sensible alternative to quantum theory and have never been directly falsified by any experiment. Here we show that fundamentally binary theories are experimentally testable with current technology. For that, we identify a feasible Bell-type experiment on pairs of entangled qutrits. In addition, we prove that, for any $n$, quantum $n$-ary correlations are not fundamentally $(n-1)$-ary. For that, we introduce a family of inequalities that hold for fundamentally $(n-1)$-ary theories but are violated by quantum $n$-ary correlations.

• Received 23 November 2016

DOI:https://doi.org/10.1103/PhysRevA.96.032104