  Causality is a seminal concept in science: Any research discipline, from
sociology and medicine to physics and chemistry, aims at understanding the
causes that could explain the correlations observed among some measured
variables. While several methods exist to characterize classical causal models,
no general construction is known for the quantum case. In this work, we present
quantum inflation, a systematic technique to falsify if a given quantum causal
model is compatible with some observed correlations. We demonstrate the power
of the technique by reproducing known results and solving open problems for
some paradigmatic examples of causal networks. Our results may find
applications in many fields: from the characterization of correlations in
quantum networks to the study of quantum effects in thermodynamic and
biological processes.
