2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/75869We generalize the classical coorbit space theory developed by Feichtinger and Gr"ochenig to quasi-Banach spaces. As a main result we provide atomic decompositions for coorbit spaces defined with respect to quasi-Banach spaces. These atomic decompositions are used to prove fast convergence rates of best $n$-term approximation schemes. We apply the abstract theory to time-frequency analysis of modulation spaces $M^{p,q}_m$, $0< p,q \leq \infty$.27 pagesFunctional Analysis42C15, 42C40, 46A16, 46E10, 46E30text