Towards Solid-State Spin Based, High-Fidelity Quantum Computation

This thesis is divided into two parts. Both of them investigate current topics in quantum information processing. The first employs super-resolving stimulated emission depletion (STED) fluorescence microscopy for the characterization of solid-state spins as a resource for quantum information processing. The other focuses on the high-fidelity control of single quantum bits. In the first part, a custom built STED microscope is utilized to demonstrate imaging of the “Stuttgart 1” (ST1) center with a spatial resolution unlimited by the diffraction of light. The bright fluorescence of the ST1 center in combination with its spin properties make it a promising candidate for quantum information processing and quantum sensing applications. Furthermore, the STED imaging of nitrogen vacancy (NV) center based fluorescent nuclear track detectors is presented. Here, the increased resolution could enable the extraction of the vacancy diffusion coefficient in diamond with high precision. Additionally, an improved understanding of the absorption process of ionizing radiation in matter might by obtained by the imaging of sub-cascade events. While the first is a crucial property in the generation process of NV center based quantum registers, the later is of importance in radiation treatment. In the second part, a recently proposed universal set of single-qubit superadiabtic geometric quantum gates (SAGQGs) is realized with a fidelity exceeding the error threshold for the efficient implementation of quantum error correction codes. Even though demonstrated for the NV center in diamond, the SAGQG can be realized with any quantum system featuring sufficient control of the driving field parameter. Additionally, a standardized benchmarking analysis is proposed, which identifies the most robust combination of quantum gates for a given set of modalities. It is shown that the most robust universal set of gates is in general not realized by a single quantum gate modality and varies with the physical platform. A systematic application of the benchmarking analysis to currently available noise intermediate scale quantum registers offers the potential to pave the way towards fault-tolerant quantum computation