Noncommutative Geometry Research Seminar

In the first semester of 2026/2027 the noncommutative geometry group will run a local NCG research seminar.

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List of talks

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Past Talks

1 Oct 2026: Max Schmidt (Leiden)

Title: The Quantum Hall Effect and the Hofstadter Butterfly

Abstract: In this talk we will discuss the Schrödinger operators describing the tight binding model in the integer quantum Hall effect using the example for square lattices. Especially, we will focus on the properties of their spectra which are given by the Hofstadter butterfly and discuss open questions.

Place and time: BM1.33. 16:00-17:00.

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10 Sep 2026: Matt Verhoeven (Leiden)

Title: Spectral truncations and the spectral localizer on SU(2)

Abstract: In this talk I will present parts of my master thesis. Spectral truncations in the sense of Connes-Van Suijlekom are a method to `approximate’ noncommutative spaces (C*-algebras or spectral triples) by considering only a finite amount of spectral information, typically provided by a Dirac operator. I will present this framework and its application to the manifold SU(2). Furthermore, this can be applied to determine K-theoretic invariants of SU(2) using the spectral localizer introduced by Loring and Schulz-Baldes.

Place and time: DM 1.19. 15:15-16:15.

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