Rui Barbosa

Staff Researcher

Quantum and Linear-Optical Computation

Rui Soares Barbosa is a Staff Researcher at the Quantum and Linear-Optical Computation group at INL.

His interests lie at the intersection of Computer Science, Physics, and Mathematics. Broadly speaking, his research addresses interrelated questions on quantum foundations, quantum computer science, and the mathematics of quantum theory, emphasising logical, structural, and compositional aspects.

It aims to achieve a general, structural understanding of the characteristically non-classical features of quantum systems, which sheds light on their potential – and limitations – as informatics or computational resources, thus delineating the scope of quantum advantage. An eventual hope is that such a foundational perspective can guide the development of systematic, modular methods for utilising quantum resources. In pursuing these goals, his research employs viewpoints and tools from a range of areas in mathematics and theoretical computer science, including category theory (sheaves, monoidal categories, closed categories, monads and comonads, …), logic and related algebraic structures, probability, algebraic topology, and operator algebras.

In particular, most of his research to date has focused on the study of non-locality and contextuality, phenomena that set quantum theory apart from classical physical theories and which have been linked to quantum informatic advantage. In contrast with the classical case, not all observables of a quantum system can be measured and assigned values simultaneously. Contexts of jointly measurable observables provide multiple partial, classical perspectives on a quantum system. But while any two of these contexts fit nicely together, they cannot all be pasted consistently into a global perspective. This gap between local consistency and global inconsistency is what constitutes contextuality, a concept that finds an elegant expression in the language of sheaf theory.

Rui holds a BSc in Computer Science from Universidade do Minho (2009), an MSc in Mathematics and Foundations of Computer Science from the University of Oxford (2010), and a DPhil in Computer Science also from Oxford (2015), with a thesis on Contextuality in quantum mechanics and beyond. Before moving to INL, he held post-doctoral positions at Oxford (2015–2019) and the University of Edinburgh (2019–2020), and a Research Fellowship at the Simons Institute for the Theory of Computing, UC Berkeley (2017).

More details can be found on his personal webpage.

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