Laser writing of coherent colour centres in diamond

Optically active point defects in crystals have gained widespread attention as photonic systems that could be applied in quantum information technologies(1,2). However, challenges remain in the placing of individual defects at desired locations, an essential element of device fabrication. Here we report the controlled generation of single negatively charged nitrogen vacancy (NV-) centres in diamond using laser writing(3). 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. Selected NV- centres display stable, coherent optical transitions at cryogenic temperatures, a prerequisite for the creation of distributed quantum networks of solid-state qubits. 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.