I recently defended my PhD in mathematics at the University of Lille under the supervision of Alexis Virelizier. My research focuses on quantum topology and the associated higher algebraic structures.
Cité Scientifique, M3
59650 Villeneuve-d'Ascq, France
Office: M3-236 ("Bureau quantique")
Telephone: +33 (0)3 20 43 48 69
Email: matthew.cellot[at]univ-lille.fr
Quantum topology is a branch of mathematics that emerged in the late twentieth century following groundbreaking work by Jones, Drinfeld, Witten, and Kontsevich, which drastically renewed topology, particularly in low dimensions. Drawing on ideas from quantum physics, their framework has led to the construction of new manifold invariants, called quantum invariants, constructed from relevant algebraic data. One of the early successes in this direction is the Turaev–Viro invariant of 3-dimensional manifolds, defined as a state sum using the algebraic data of a fusion category (constructed for instance from the representations of a quantum group). More recently, Douglas and Reutter have constructed state-sum invariants of 4-dimensional manifolds using fusion 2-categories.
My work investigates quantum homotopy invariants, that is, quantum invariants of manifolds equipped with additional structure encoded by a map to a target topological space. More specifically, I have generalized the Douglas–Reutter construction to derive invariants of flat 3-bundles over 4-manifolds or, equivalently, of 4-manifolds equipped with a homotopy class of maps to a homotopy 3-type. The relevant algebraic input for these quantum homotopy invariants is 3-group extensions of fusion 2-categories, where the 3-group models the target homotopy 3-type. The resulting invariants are nontrivial and can even distinguish phantom maps, that is, maps that are trivial at the level of homotopy groups.
"3-group extensions of fusion 2-categories and quantum homotopy invariants of 4-manifolds", July 2026, pdf
"Graded-fusion 2-categories and quantum homotopy invariants of 4-manifolds", August 2026, arXiv:2608.20959
"Higher path groupoids and the holonomy of formal power series connections", June 2025, arXiv:2506.23880 (submitted)
"4-dimensional homotopy quantum field theories and homotopy 3-types"
May 2026 - Algebra seminar, University of Leeds
Feb 2026 - Algebraic Topology seminar, UCLouvain
Feb 2026 - Topology seminar, Université de Lille
Nov 2025 - Quantum Universe Attract. Workshop, Universität Hamburg
Sep 2025 - Higher Structures: Recent developments and applications, Universität Hamburg (see slides)
May 2025 - Algebraic Approaches to Mapping Class Groups of Surfaces, The University of Tokyo
May 2025 - FJ-LMI Seminar, The University of Tokyo (see slides)
Apr 2025 - Journées de Jeunes Chercheuses et Chercheurs en Topologie, Université Picardie Jules Verne
Nov 2024 - Séminaire des doctorants et post-doctorants, Université de Lille (see slides in French)
Jan 2024 - Topology seminar, University of Louisiana at Lafayette (see slides)
Sep 2023 - Topology seminar, Université de Lille
May 2026 - BTW6: The Volume Conjecture: from some TQFTs to recent developments, Villa Clythia Fréjus
Mar 2026 - Journées de topologie algébrique, géométrique et quantique en Picardie III, Université de Picardie Jules Verne
Mar 2026 - Winter braids XV, Aix-Marseille Université
Oct 2025 - Journée de topologie quantique, Université Paris Cité
Sep 2025 - Higher Structures: Recent developments and applications, Universität Hamburg
May 2025 - Algebraic approaches to mapping class groups of surfaces, The University of Tokyo
Apr 2025 - Journées de Jeunes Chercheuses et Chercheurs en Topologie, Université de Picardie Jules Verne
Mar 2025 - Journées de topologie algébrique, géométrique et quantique en Picardie II, Université de Picardie Jules Verne
Feb 2025 - Winter braids XIV, Université de Bordeaux
Dec 2024 - Skein days, Journées thématiques de Cergy-Pontoise, CY Cergy Paris Université
Nov 2024 - Journée de topologie quantique, Université Paris Cité
Oct 2024 - Séminaire itinérant de catégories, Université Paris Cité
Oct 2024 - Higher structures in Noncommutative Geometry and Quantum Algebra, Université de Lille
Sep 2024 - Scottish Talbot on Algebra and Topology, Cairngorm Lodge, Glenmore, Scotland
Apr 2024 - Séminaire itinérant de catégories, Université de Lille
Mar 2024 - Journées de topologie algébrique, géométrique et quantique en Picardie, Université de Picardie Jules Verne
Mar 2024 - Journée de topologie quantique, Université Paris Cité
Feb 2024 - Winter braids XIII, Université de Montpellier
Oct 2023 - Conférence du GDR Théorie de l'Homotopie et Applications, Université de Lille
Oct 2023 - Séminaire itinérant de catégories, Université du Littoral à Calais
Mar 2023 - Building-up differential homotopy theory at Aizu, The University of Aizu
Feb 2023 - 18th East Asian Conference on Geometric Topology, online
Nov 2022 - International conference on "Topology and its Applications to Engineering and Life Science", online
Mathématiques et biostatistiques (24h TD) L2 Sciences et la vie
Algèbre et analyse élémentaires 2 (36h TD) L1 Physique
Éléments d'algorithmique (4h TD) L2 Informatique
Tutorat (24h TD) L1-L2-L3 Mathématiques
Algèbre et analyse élémentaires 2 (36h TD) L1 Physique
Internship supervisor for Valentin Gianesello, L1 Physique
"Constructions of 2-holonomy functors", ARPE report, 2023, under the supervision of Toshitake Kohno
"Sur la topologie des surfaces algébriques réelles non singulières de degré au plus 5 dans RP^3", master's thesis, 2022 (in French), under the supervision of Ilia Itenberg
"The invariance of knot lattice homology", first year master's project, 2021
"Contrefaçon d'une œuvre musicale : comment déterminer le plagiat ?", research project in law and mathematics, 2023, with Thomas Hum (see poster)