Forum de Physique Statistique à l'École Normale Supérieure

Next seminars

8 April, 11h, E239 (library, 24 rue Lhomond)

Partition function of the Kitaev quantum double model

Jean-Noël Fuchs (LPTMC Paris, CNRS and Sorbonne Université)

In this talk, I will discuss our recent work on topological order at finite temperature, computing in particular the partition function of the Kitaev quantum double [1]. This is an exactly-solvable toy model built on a discrete group and on a 2D lattice and realizing deconfined anyonic excitations. Its simplest instance is the famous toric code model built from the Z_2 group. This model allows one to describe many phases with achiral topological order. We find that this type of topological order is destroyed at finite temperature in the thermodynamic limit. However, in a finite-size system, there is a finite temperature below which topological order is preserved.

[1] A. Ritz-Zwilling, B. Douçot, S. H. Simon, J. Vidal, J.-N. Fuchs, “Partition function of the Kitaev quantum double model”, arxiv:2509.10876 (to appear in PRB 2026)

Upcoming seminars

15 April, Sarah Loos