It is hard to overestimate the impact of the Cavendish Laboratory’s on the development of fundamental physics theories, from its establishment, well into the 20th century. Today, the biggest questions of the foundations of physics concern the fundamentals of quantum theory, and their relation to general relativity. On a global perspective, the research of the foundations of quantum mechanics is advanced by a small number of groups. Given the extraordinary success of quantum theory in progressing physical sciences and technology, it is remarkable how little is known of the foundations of the theory itself. Current research fields include: the interpretation of quantum mechanics and the measurement problem; the reconciliation of quantum mechanics and classical statistics via quasi-probability formalisms; the localisation of quantum-classical barriers via the study of quantum negativity and contextuality; the reconciliation of quantum mechanics with general relativity, for example, via the study of quantum mechanical closed time-like curves; and the extension of classical information theory to quantum information theory. Results regarding, for example, generalised contextuality and quantum negativity, have improved our ability to incur quantum advantages in technologies. Consequently, an increasing amount of funding is allocated to foundational research.
Given the historical role of the University of Cambridge in the development of quantum mechanics, the Cavendish QI group plays a natural role in the research of quantum foundations. The group conducts research on three separate areas of quantum foundations. First, the group investigates the fundamental relation between information transmission and matter propagation (as outlined above). Second, the group is currently developing quasi-probabilistic tools for the statistical treatment of quantum experiments and the determination of underlying quantum-advantage mechanisms. Third, the group is working on group-theoretic aspects of entanglement and separability.