Metric aspects of noncommutative homogeneous spaces

Abstract

For a closed cocompact subgroup $Γ$ of a locally compact group $G$, given a compact abelian subgroup $K$ of $G$ and a homomorphism $ρ:\hat{K}\to G$ satisfying certain conditions, Landstad and Raeburn constructed equivariant noncommutative deformations $C^*(\hat{G}/Γ, ρ)$ of the homogeneous space $G/Γ$, generalizing Rieffel's construction of quantum Heisenberg manifolds. We show that when $G$ is a Lie group and $G/Γ$ is connected, given any norm on the Lie algebra of $G$, the seminorm on $C^*(\hat{G}/Γ, ρ)$ induced by the derivation map of the canonical $G$-action defines a compact quantum metric. Furthermore, it is shown that this compact quantum metric space depends on $ρ$ continuously, with respect to quantum Gromov-Hausdorff distances.