English

Noncommutative geometry on the Berkovich projective line

Functional Analysis 2026-04-10 v2 Number Theory Operator Algebras Quantum Algebra

Abstract

We construct several CC^*-algebras and spectral triples associated to the Berkovich projective line PBerk1(Cp)\mathbb{P}^1_{\mathrm{Berk}}({\mathbb{C}_p}). In the commutative setting, we construct a spectral triple as a direct limit over finite R\mathbb{R}-trees. More general CC^*-algebras generated by partial isometries are also presented. We use their representations to associate a Perron-Frobenius operator and a family of projection valued measures. Finally, we show that invariant measures, such as the Patterson-Sullivan measure, can be obtained as KMS-states of the crossed product algebra with a Schottky subgroup of PGL2(Cp)\mathrm{PGL}_2(\mathbb{C}_p).

Keywords

Cite

@article{arxiv.2411.02593,
  title  = {Noncommutative geometry on the Berkovich projective line},
  author = {Masoud Khalkhali and Damien Tageddine},
  journal= {arXiv preprint arXiv:2411.02593},
  year   = {2026}
}
R2 v1 2026-06-28T19:48:09.121Z