Order-unit quantum Gromov–Hausdorff distance

Abstract

We introduce a new distance dist oq between compact quantum metric spaces. We show that dist oq is Lipschitz equivalent to Rieffel's distance dist q , and give criteria for when a parameterized family of compact quantum metric spaces is continuous with respect to dist oq . As applications, we show that the continuity of a parameterized family of quantum metric spaces induced by ergodic actions of a fixed compact group is determined by the multiplicities of the actions, generalizing Rieffel's work on noncommutative tori and integral coadjoint orbits of semisimple compact connected Lie groups; we also show that the θ -deformations of Connes and Landi are continuous in the parameter θ .