The group "Crystals and Quantum State Dynamics" (www.cqsd.fr) at IRCP (Chimie ParisTech/CNRS/PSL University), led by Dr. Philippe Goldner, is internationally recognized for developing rare earth doped crystals for applications in quantum technologies. These materials show unique properties in the solid-state in terms of long optical and spin coherence lifetimes, and are thus among the most promising materials for building light-matter interfaces at the quantum level.