Quantum mechanics developed at the beginning of the last century has now entered the Second Revolution. Different experimental implementations such as trapped ions, superconducting circuits, color centers, cold atoms, and quantum dots in semiconductor materials have been used in the field of quantum technologies. The color centers in large band gap materials are among the most promising candidates for quantum applications. A paradigmatic example is the nitrogen-vacancy (NV) center in diamond. Its spin state can be initialized and optically readout and has long coherent time for the electron spin and the nuclear spin. Based on these remarkable properties, we are studying color centers in different materials for applications in quantum technologies.