  Bell's theorem prompts us with a fundamental inquiry: what is the simplest
scenario leading to the incompatibility between quantum correlations and the
classical theory of causality? Here we demonstrate that quantum
non-classicality is possible in a network consisting of only three dichotomic
variables, without the need of the locality assumption neither external
measurement choices. We also show that the use of interventions, a central tool
in the field of causal inference, significantly improves the noise robustness
of this new kind of non-classical behaviour, making it feasible for
experimental tests with current technology.
