I use quantum information tools to ask fundamental questions on the nature of spacetime, causality, and gravity at the intersection of quantum theory and general relativity. In particular, I have so far focussed on some features that could arise as a consequence of nonclassical spacetime: indefiniteness of causal relations and generalised transformations between two reference frames in a quantum relation with each other. In addition, I am interested in exploring the effects that a quantum theory of gravity would manifest in the low-energy regime, and how they could soon be tested in the laboratory.