
Quantum entanglement between an optical photon and a solid-state spin qubit. Temporal coherence of photons emitted by single nitrogen-vacancy defect centers in diamond using optical Rabi oscillations. Prospects for measurement-based quantum computing using solid state spins. Efficient high-fidelity quantum computation using matter qubits and linear optics. Germanium-vacancy single color centers in diamond. Identification and magneto-optical properties of the NV center in 4 H–SiC. Coherent control of single spins in silicon carbide at room temperature. Isolated electron spins in silicon carbide with millisecond coherence times. All-optical initialization, readout, and coherent preparation of single silicon-vacancy spins in diamond. Optical signatures of silicon-vacancy spins in diamond. Resonant addressing and manipulation of silicon vacancy qubits in silicon carbide. Observation of coherent oscillations in a single electron spin. Jelezko, F., Gaebel, T., Popa, I., Gruber, A. Femtosecond laser micromachining in transparent materials. Quantum computing: diamond and silicon converge.

The results illustrate the potential of laser writing as a new tool for defect engineering in quantum technologies, and extend laser processing to the single-defect domain.

Selected NV − centres display stable, coherent optical transitions at cryogenic temperatures, a prerequisite for the creation of distributed quantum networks of solid-state qubits. Aberration correction in the writing optics allows precise positioning of the vacancies within the diamond crystal, and subsequent annealing produces single NV − centres with a probability of success of up to 45 ± 15%, located within about 200 nm of the desired position in the transverse plane. Here we report the controlled generation of single negatively charged nitrogen–vacancy (NV −) centres in diamond using laser writing 3.

However, challenges remain in the placing of individual defects at desired locations, an essential element of device fabrication. Optically active point defects in crystals have gained widespread attention as photonic systems that could be applied in quantum information technologies 1, 2.
