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KMS states on $C_c^{*}(\mathbb{N}^2)$

Published online by Cambridge University Press:  03 April 2023

Anbu Arjunan
Affiliation:
Indian Statistical Institute, Delhi Centre, NewDelhi, 110016, India
Sruthymurali
Affiliation:
Indian Statistical Institute, Bangalore Centre, Bangalore, 560059, India
S. Sundar*
Affiliation:
Institute of Mathematical Sciences (HBNI), Chennai, 600113, India
*
*Corresponding author. E-mail: sundarsobers@gmail.com

Abstract

Let $C_c^{*}(\mathbb{N}^{2})$ be the universal $C^{*}$-algebra generated by a semigroup of isometries $\{v_{(m,n)}\,:\, m,n \in \mathbb{N}\}$ whose range projections commute. We analyse the structure of KMS states on $C_{c}^{*}(\mathbb{N}^2)$ for the time evolution determined by a homomorphism $c\,:\,\mathbb{Z}^{2} \to \mathbb{R}$. In contrast to the reduced version $C_{red}^{*}(\mathbb{N}^{2})$, we show that the set of KMS states on $C_{c}^{*}(\mathbb{N}^{2})$ has a rich structure. In particular, we exhibit uncountably many extremal KMS states of type I, II and III.

Type
Research Article
Copyright
© The Author(s), 2023. Published by Cambridge University Press on behalf of Glasgow Mathematical Journal Trust

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