Quantum information processing has made huge progress in recent decades. Thanks to exceptional controllability of the quantum states of spins of individual color centers in diamond and superconducting qubits, these approaches are leading technologies of solid-state-based quantum computing. Isolated spins in diamonds only weakly couple to the environment and show long coherence times. Nanometer accuracy is required to integrate individual atoms into quantum registers on a large scale. Registers of superconducting qubits are easier to realise, but their macroscopic nature leads to shorter relaxation times. Therefore, hybrid approaches from superconducting qubits and diamond-based spin qubits are attractive for scalable approaches. A linking of long-lasting qubits to optical photons allows entanglement over long distances. Here we realise a link between quantum states of optical photons, spins in diamonds and superconducting qubits.