Rui Soares Barbosa
Rui Miguel de Sousa Martinho Soares Barbosa
Wolfson Building, Parks Road, Oxford OX1 3QD
Interests
Broadly speaking, I am interested in the foundations of Physics, particularly of quantum mechanics and quantum information/computation, and in their interplay with several areas of mainstream computer science.
My current research focuses on the following two topics:
 The study of nonlocality, contextuality and other related concepts in general empirical models, concretely using the sheaftheoretic framework developed by Abramsky and Brandenburger for generalised (nosignalling) probabilistic theories. On recent work, I looked at monogamy of nonlocality and the emergence of locality at the macroscopic level. I've recently also been looking at some surprising connections with database theory, related to the notions of informational dependence and independence.
 The topos approach to quantum theory initiated by Isham, Butterfield and Döring, which seeks a reformulation of quantum mechanics using presheaves to capture all the different classical (partial) perspectives into a quantum system. I'm particularly interested in a logic of approximation associated to these partial contexts, in the spectral presheaf as an analogue of state space for noncommutative algebras, and in the connections with the covariant version of the approach.
Despite the different goals and purposes of each of these lines of research, they share both some motivational and technical characteristics, in regarding contextuality as a fundamental feature of quantum mechanics and in using the language of (pre)sheaves to study a system through its 'classical perspectives' (sets of compatible/commuting observables).
Biography
 Aug 2016 – Dec 2016
 Simons–Berkeley Research Fellow
 Programme: Logical Structures in Computation
 Simons Institute for the Theory of Computing, University of California, Berkeley

 Jan 2015 –
 Research Assistant in the Quantum Group
 Department of Computer Science, University of Oxford
 Jan 2016 – Dec 2018: Junior Research Fellow, Wolfson College, Oxford

 Oct 2010 – Jul 2015
 DPhil in Computer Science
 Department of Computer Science, University of Oxford
 under the supervision of Samson Abramsky and Andreas Döring.
 Oct 2010 – Sep 2013: ESR fellow of the MALOA project.
 Jan 2014 – Dec 2014: funded by FCT

 Oct 2009 – Sep 2010
 MSc in Mathematics and the Foundations of Compter Science (aka MFoCS)
 Mathematical Institute and Computing Laboratory (now Dept. of Computer Science), University of Oxford
 My dissertation supervisor was Andreas Döring.

 Sep 2006 – Jul 2009
 Licenciatura (BSc) in Computer Science
 Departments of Mathematics and Informatics, Universidade do Minho, Braga.
 Feb 2009 – Jun 2009: Semester Erasmus programme at Center for Software Technology, Utrecht Universiteit
Selected Publications

Contextuality and noncommutative geometry in quantum mechanics
Nadish de Silva and Rui Soares Barbosa
2018.
Accepted to appear in Communications in Mathematical Physics; Earlier partial version (“Partial and total ideals of von Neumann algebras”) available as arXiv:1408.1172 [math.OA]
Details about Contextuality and noncommutative geometry in quantum mechanics  BibTeX data for Contextuality and noncommutative geometry in quantum mechanics

Contextual fraction as a measure of contextuality
Samson Abramsky‚ Rui Soares Barbosa and Shane Mansfield
In Physical Review Letters. Vol. 119. No. 050504. 2017.
E−print: arXiv:1705.07918 [quant−ph]; Earlier version (“Quantifying contextuality via linear programming”) accepted for communication to 13th International Conference on Quantum Physics and Logic (QPL 2016).
Details about Contextual fraction as a measure of contextuality  BibTeX data for Contextual fraction as a measure of contextuality  DOI (10.1103/PhysRevLett.119.050504)  Link to Contextual fraction as a measure of contextuality

A complete characterization of All−versus−Nothing arguments for stabilizer states
Samson Abramsky‚ Rui Soares Barbosa‚ Giovanni Carù and Simon Perdrix
In Philosophical Transactions of the Royal Society of London A: Mathematical‚ Physical and Engineering Sciences‚ Theme Issue on ‘Second quantum revolution: foundational questions'. No. 2106. 2017.
E−print: arXiv:1705.08459 [quant−ph]
Details about A complete characterization of All−versus−Nothing arguments for stabilizer states  BibTeX data for A complete characterization of All−versus−Nothing arguments for stabilizer states  Link to A complete characterization of All−versus−Nothing arguments for stabilizer states