Quantum Statistical Mechanics of $\mathbb{Q}$-lattices and   noncommutative geometry
  After recalling some basic notions of quantum statistical mechanics, we explain the Bost-Connes system that relates the structure of the maximal abelian extension of $\mathbb{Q}$ to the space of \kms states of a \cs-dynamical system. Afterwards, we study briefly the Connes-Marcolli $\text{GL}_2$-system as a generalization of the former system. 
Vahid Shirbisheh