In this talk, I will discuss the development of semi-classical analysis for sub-elliptic operators such as sub-Laplacians. For an elliptic operator, this is well understood as the tools and methods to study e.g. quantum ergodicity or Schrödinger equations have become well established over the past fifty years. They rely on the pseudo-differential theory, and in the elliptic case the space of principal symbols is commutative. The aim of this talk is to present my approach to define similar tools for sub-Laplacians, leading to more non-commutative concepts.