Guest Seminar hosted by CDQT.
Speaker: Dr.Thore Posske(University of Hamburg)
Title: Synthesizing quantum matter with magnetic and nonmagnetic adatoms on superconductors — the topological secrets of hybridizing Machida-Shibata states
 

Dr. Caroline L. Monteil, Senior Researcher at Aix-Marseille University, CEA, CNRS, Biosciences and Biotechnologies Institute of Aix-Marseille, Saint-Paul-lez-Durance, France

Michael Lathwood (OIST): October 19, 4pm-5pm, lecture room L5D23.

Title: Counting Tensor Invariants with Defect TQFT 

Abstract: A tensor transforming under a unitary-orthogonal symmetry group carries finitely many invariant observables of each degree. Counting these so-called tensor invariants is an important problem in the theory of tensor models, and it reduces to counting tuples of permutations modulo a conjugation action.

In this talk, I will explain how this counting can be interpreted as the partition function of an untwisted Dijkgraaf-Witten topological quantum field theory with defects. The permutations groups appearing in the tensor invariant counting problem are exactly the defect data of a stratified manifold, and the tensor invariant is then the groupoid cardinality of the associated gauge groupoid. I conclude with physics applications coming from this perspective of tensor invariants.

This talk is based on forthcoming joint work with Remi Cocou Avhou, Noan Botcazou-Brasse, and Reiko Toriumi. 

[Seminar] "Direct measurement of coupling distance by Flash & Freeze-fracture replica labeling" by Prof. Ryuichi Shigemoto, Institute of Science and Technology Austria (ISTA)

November 27, 2026  11:00-12:00 @L5D23

Title: From dislocation dynamics to Hamilton-Jacobi equations: homogenization and the Orowan mechanism

Speaker: Dr. Panrui Ni (Waseda University)

Seminar by Prof. Spatafora

Mr. Hongda Zhao, Kyoto University

Speaker: Dr. Sascha Sadewasser, Iberian Nanotechnology Laboratory (INL), Portugal

Cristina Ana-Maria Anghel (Université Clermont Auvergne): October 13, 4pm-5pm, lecture room L5D23 (online talk).

Title: Universal Link Invariants via Configuration Spaces

Abstract: Coloured Jones and Alexander polynomials are quantum invariants originating in representation theory and their geometric information is an important open problem in quantum topology. We present a new topological perspective that unifies these invariants through the topology of configuration spaces. First, for a fixed N, we define new link invariants: "N-th Unified Jones invariant" and "N-th Unified Alexander invariant" globalising all coloured Jones and ADO link polynomials of (multi)-colours bounded by N. Asymptotically, Habiro defined his universal knot invariant globalising coloured Jones polynomials by introducing the Habiro ring. For the link case, such globalisation remained open for both sequences of invariants. We answer this problem coming from representation theory using topological tools. On the representation theory side we define extensions of Habiro type rings. On the topological side, we construct a universal Jones link invariant and a universal Alexander link invariant. Putting these together, our universal invariants of geometrical nature take values in the extended Habiro rings that we construct. 

Paul Feehan (Rutgers University): October 13, 2:30pm-3:30pm, lecture room L5D23.

Title:  Towards a Bogomolov-Miyaoka-Yau inequality for symplectic 4-manifolds, II

Abstract: The Bogomolov-Miyaoka-Yau inequality for minimal compact complex surfaces of general type was proved in 1977 independently by Miyaoka, using methods of algebraic geometry, and by Yau, as an outgrowth of his proof of the Calabi conjectures. In this talk, we describe progress in our ongoing program to prove the conjecture that symplectic 4-manifolds obey the Bogomolov-Miyaoka-Yau inequality. Our program uses Morse theory on the gauge theoretic moduli space of non-Abelian monopoles, where the Morse function is a Hamiltonian for a natural circle action and natural two-form. We shall describe generalizations of Donaldson’s symplectic subspace criterion (1996) from finite to infinite dimensions and generalizations of Taubes' perturbation analysis from the Seiberg-Witten to non-Abelian monopole equations. These methods have application to the problem of showing that the fundamental two-form is non-degenerate and thus an almost symplectic form on the moduli space of non-Abelian monopoles. This talk is based on joint work with Tom Leness and the monographs https://arxiv.org/abs/2010.15789 (to appear in AMS Mathematical Surveys and Monographs),  https://arxiv.org/abs/2206.14710  and https://arxiv.org/abs/2410.13809.