Basic Science for Quantum Technologies (RIA) Proposals should aim to explore new quantum effects and gain new knowledge that is not limited to the pillar activities, and which may contribute to new quantum technologies and applications in the long term. Areas of particular interest include quantum information theory, the identification of new laws and limits, understanding the mechanisms behind decoherence, the development of certification methods for quantum technologies, and research that goes beyond the field of pure quantum technologies, such as the study of quantum effects in thermodynamic or biological processes.The technological resources include strategic components, ranging from fundamental properties to engineering quantum devices and systems (TRL 2-4) to interfacing these across different, always with a view towards end-user applications and their operation. Examples are: light sources, interfaces including manipulation of light, and single photon detectors, which are compatible and interoperable. The development of new materials, single integrated solutions or hybrid integrated solutions that are miniaturised and scalable, fabrication and packaging solutions, are also key challenges, as is the development of new protocols, control approaches and algorithms.Proposals should contribute to (i) the governance and overall coordination of the Quantum Technologies Flagship initiative, (ii) where relevant to inter-project cooperation, in particular with the 4 main pillars of the Quantum Technologies Flagship (quantum computing, quantum simulation, quantum communication and quantum sensing and metrology). They should also contribute to spreading excellence across Europe; for example, through the involvement of Widening Countries.In this topic the integration of the gender dimension (sex and gender analysis) in research and innovation content is not a mandatory requirement.