Laser writing of coherent colour centres in diamond

Thesis

Optical 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%, located within about 200nm of the desired position in the transverse plane. A simple model was established to understand the mechanism of vacancies generation and estimate the success probability of NV- centres generation. Selected NV- centres display stable, coherent optical transitions at cryogenic temperatures, a prerequisite for the creation of distributed quantum networks of solid-state qubits. Strain measurement results of selected NV- centres show that the broadening of NV- optical transitions is due to local strain. The results illustrate the potential of laser writing as a tool for defect engineering in quantum technologies and extend laser processing to the single-defect domain.

Authors: Chen, Y

• DOI: 10.5287/ora-eq2n8zwdm
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford