Transdisciplinarity is increasingly seen as a promising paradigm for strong sustainability. Following a common typology, two "Modes" of transdisciplinary can be distinguished: A theoretical "Mode 1", largely inspired by quantum theory, and a practical "Mode 2" transdisciplinarity involving multi-stakeholder's approaches. So far, Mode 1 and 2 have been developed independently. In this communication, I discuss the potential of using insights from quantum theory to foster deep transformations toward strong sustainability, by closing this gap between Mode 1 and 2. As a first example, I show how a generalization of the quantum complementarity principle to sustainability assessment can be used to better address two major issues (integration and implementation). Then, I explore how quantum insights suggest powerful sustainable pathways, by shedding light on subjectivity, the possibility of free-will and the "co-arising" of personal and systemic change. Finally, a general strategy is proposed, that combine robust quantum methodological insights with a careful exploration of ontological insights.