Single defects in solids may realize bright single photon sources and qubits that can be probed by optical measurements combined with electron spin resonance techniques. Some optical centers exhibit spin-selective fluorescence where the spin state can be coherently manipulated, and its spin state can be read out by optical means, called optically detected magnetic resonance (ODMR). An ODMR laboratory should be developed to measure single photon sources and single spins in solids, and the magneto-optical properties of the centers should be determined. These single spins will be created in diamond, silicon carbide, and related materials. These observations may contribute to the realisation of single photon sources for quantum communication or solid state qubits for quantum sensing. These studies will be carried out in close collaboration with domestic and international partners. Training is available in the laboratories of the Physics Institute of the Budapest University of Technology and Economics and the University of Vienna.