Avatar of Yuezhao Li
Yuezhao Li
Mathematical Institute
Leiden University
Netherlands
y.li@math.leidenuniv.nl

I am a PhD candidate in mathematics at Leiden University, studying noncommutative geometry (NCG) and its applications in index theory and mathematical physics. My supervisor is Dr. Bram Mesland.

From 2013 to 2018, I studied physics and mathematics at Peking University, China. From 2018 to 2021, I studied mathematics at Georg-August-Universität Göttingen, Germany, specialising in noncommutative geometry and its application in topological insulators. I wrote my master thesis under the supervision of Prof. Dr. Ralf Meyer.

Besides mathematics, I am also an enthusiastic long-distance runner.

Research. The "noncommutative essence" of the real world suggests the possibility of NCG being a language of physics. One of the most successful attempts was provided by the seminal work of Jean Bellissard and his collaborators on the integer quantum Hall effect. Since then, C*-algebras and K-theory are prominent in understanding solid state systems, in particular, topological insulators. Motivated by the work of Bourne and Mesland on index theory of aperiodic topological insulators, and Meyer's work on groupoid correspondences, I am reconsidering the structure of C*-algebras modelling topological insulators, and attempting to provide a novel approach with techniques of groupoids correspondences and partial dynamical systems.

Recent focus of my research is about index theory of finite spectral truncations, namely, how to obtain numerical index pairings using only finite-dimensional spectral data that come from a finite energy cut-off of an infinite dimensional spectral triple. There have been several successful attempts, among which there is Schulz-Baldes and Loring's spectral localisers. Ongoing work of mine will provide a systematic understanding of this and similar techniques in literature.


Calendar 2024

I will attend OdenSeaG 2024, which will take place during 19-23 August, 2024 in Odense.

From 31 August to 8 September, I will be visiting Sichuan University, Chengdu, China.

From 9 September to 14 September, I will be visiting East China Normal University, Shanghai, China.

In early October, I will be visiting Peking University, Beijing, China.

In the upcoming 2024 fall semester, I will be tutoring the Dutch national mastermath course "Functional Analysis" taught by Marcel de Jeu and Onno van Gaans. This will likely be my last time to assist with this course, from which I have learnt quite much.


NCG-Leiden

I am a maintainers of NCG-Leiden (together with Yufan Ge and Francesca Arici), a webpage collecting and announcing the information of local NCG seminars at Leiden University. In 2024 spring semester, Francesca Arici and Bram Mesland are running a research seminar on Wednesdays from 15:15-16:15. If you want to be added to the mailing list for this seminar, please contact Francesca Arici or Bram Mesland.

In March 2024, Adam Rennie gave a mini-course on connections and curvatures in NCG, based on joint work of him and Bram Mesland.

In previous semesters, we have run reading seminars on noncommutative geometry of foliations (2023 fall), groupoid C*-algebras (2022 fall) and KK-theory (2022 spring).


Notes and Handouts

I have taken notes for several lectures and seminars. Some of them are below. They may be incomplete and contain mistakes. Please use at your own risk.


Talks

  1. 30/05/2024: A hitchhiker’s guide to topological insulators in noncommutative geometry. Leiden-Birmingham Meeting.
  2. 01/11/2023: Noncommutative geometry in index theory and physics. Leiden-Luxembourg PhD Away Day.
  3. 10/10/2023: Models of aperiodic topological insulators. My lightning talk given at Autumn School on Large Scale Geometry, 9-13 October 2023, Göttingen.

Teaching


Events, Conferences and Workshops


Personal

I am an eager runner, and a learner in German and Dutch.

Running

I enjoy long-distance running. As an undergraduate student at Peking university, I was a member of PURA (Peking university runners' association). I paused running for several years but rediscovered my passion during the pandemic in 2021. Despite of those enumerous annoying injuries, running brings me far more pleasure and confidence.

Uitslagen:

  1. 14/07/2024: Halbmarathon @ 14. Ermstal-Marathon, Metzingen, Germany. Finish in 1:35:46. Rank: 73/664.
  2. 16/06/2024: 15km @ 13e Yanmar Almere City Run, Almere, Netherlands. Finish in 1:06:47. Rank: 47/461.
  3. 12/05/2024: Halve Marathon @ 33e Leiden Marathon, Leiden, Netherlands. Finish in 1:35:33 (Personal Best). Rank: 249/5370.
  4. 10/03/2024: Halve Marathon @ 48e NN CPC Loop Den Haag, den Haag, Netherlands. Finish in 1:37:48. Rank: 2473/13564.
  5. 26/11/2023: Halve Marathon @ 18e Spijkenisse Marathon, Spijkenisse, Netherlands. Finish in 1:38:29. Rank: 142/589.

Languages and linguistics

Ich lerne Deutsch und Niederländisch. Ich interessiere mich auch für die Geschichte der germanischen Sprachen. Ich finde, dass es sehr hilfreich ist, deutsche Mathematikartikel zu lesen, um mein Deutsch zu lernen.