I am a mathematician working on interactions between graph theory, quantum information theory, quantum groups, and operator algebras.

Brief CV:

• 2025–present: Postdoc, Department of Applied Mathematics, 🇨🇿 Charles University.
  Working with: Mykhaylo Tyomkyn.
• 2023–2025: Postdoc, Algorithms, Logic and Graphs, 🇩🇰 Technical University of Denmark.
  Working with: David E. Roberson.
• 2018–2023: PhD student, Discrete Math & Optimization, 🇳🇱 Delft University of Technology.
  Supervisors: Dion Gijswijt and Onno van Gaans.

My name is Dutch and consists of three parts: {First}{von}{Last}{Jr.} = {Josse}{van}{Dobben de Bruyn}{}. It should be alphabetized under “Dobben”.

Profiles: MathSciNet • zbMATH • ORCID • Google Scholar • arXiv

Research interests

I work in the emerging interdisciplinary field of “quantum graph theory”, part of the wider field of “Operator Algebras & Quantum Information”. Among other things, this field studies quantum versions of graph-theoretic concepts such as chromatic number, independence number, homomorphisms, and isomorphism. These concepts are tied to nonlocal games, but also to quantum groups (the quantum automorphism group of a graph), thereby forming a bridge between quantum information theory and quantum groups. One of the highlights of this field is a result by Mančinska and Roberson, who used representation theory of quantum groups to prove that two graphs are quantum isomorphic if and only if they have the same number of homomorphisms from every planar graph (extended abstract, arXiv paper).

I mainly work on combinatorial and algebraic questions in this field, but occasionally also on the functional analytic side. My recent contributions include:

• Helping develop combinatorial tools to compute quantum automorphism groups of certain families of graphs (e.g. trees, outerplanar graphs, lexicographic products of graphs);
• Finding the first known examples of graphs with trivial automorphism group and non-trivial quantum automorphism group, which shows that even graphs with no symmetry at all can have quantum symmetry;
• Showing that no commutativity gadgets exist for certain quantum CSPs (constraint satisfaction problems), including \(k\)-colouring for all \(k \geq 4\).

My broader research interests include algebraic combinatorics, functional analysis, and quantum information theory. I have coauthored papers on various topics in these fields; see my research page.

Selected publications

• Josse van Dobben de Bruyn, David E. Roberson, and Simon Schmidt.
  Asymmetric graphs with quantum symmetry.
  Proceedings of the London Mathematical Society, to appear.
• Arnbjörg Soffía Árnadóttir, Josse van Dobben de Bruyn, Prem Nigam Kar, David E. Roberson, and Peter Zeman.
  Quantum automorphism groups of lexicographic products of graphs.
  Journal of the London Mathematical Society 111(4):#e70141, 2025. doi:10.1112/jlms.70141.
• Josse van Dobben de Bruyn, Prem Nigam Kar, David E. Roberson, Simon Schmidt, and Peter Zeman.
  Quantum automorphism groups of trees.
  Journal of Noncommutative Geometry, Online First articles, 2025. doi:10.4171/jncg/607.
• Josse van Dobben de Bruyn.
  Tensor products of convex cones.
  Preprint, 101 pages, arXiv:2009.11843.
• Josse van Dobben de Bruyn, Harry Smit, and Marieke van der Wegen.
  Discrete and metric divisorial gonality can be different.
  Journal of Combinatorial Theory, Series A 189:#105619, 2022. doi:10.1016/j.jcta.2022.105619.
• Josse van Dobben de Bruyn and Dion Gijswijt.
  Treewidth is a lower bound on graph gonality.
  Algebraic Combinatorics 3(4):941–953, 2020. doi:10.5802/alco.124.

For the full list of publications, please refer to my research page.