.. _research_solids: Quantum Information with Solid-State Defect Centers =================================================== Solid-state defect centers, like nitrogen-vacancy centers in diamonds, are promising candidates for **quantum information processing** and **quantum sensing**. The **quantum coherence** of the defect center spins is an essential parameter, which determines the number of logic operations available in quantum information processing and the sensitivity in quantum sensing. We are interested in the theory of spin decoherence, the method of controlling spins to protect the coherence, and various applications such as using solid-state defect centers to implement single-molecular NMR. Decoherence of central spins ------------------------------ We studied central spin decoherence problems in various solid-state systems, including nitrogen-vacancy centers in diamond, di-vacancy centers in silicon-carbide, rare-earth atoms in YAG/YSO crystals, and radical electrons in molecular crystal. - Nitrogen-vacancy centers in diamond [`Physical Review B 85, 115303 (2012) `_] .. figure:: ./_static/research_NVcoherence.jpg :width: 400px :align: left :alt: Coherence of NV center :figwidth: 100% Different decoherence behavior of NV centers in diamond in different magnetic fields. - Di-vacancy centers in SiC [`Physical Review B 90, 241203(R) (2014) `_] .. figure:: ./_static/research_Divacancycoherence.jpg :width: 400px :align: left :alt: Coherence of divacancy center :figwidth: 100% Microscopic mechanisms of di-vacancy centers decoherence in SiC. - Rare-earth atoms in YAG [`Nature Communications 5, 3895 (2014) `_] .. figure:: ./_static/research_RearEarthYAG.jpg :width: 400px :align: left :alt: Coherence of rear-earth atoms :figwidth: 100% Rare-earth atoms decoherence in YAG crystal under dynamical decoupling control. - Radical spins in malonic-acid crystal [`Nature 461, 1265 (2009) `_] .. figure:: ./_static/research_radical.jpg :width: 400px :align: left :alt: radical spins in malonic acid :figwidth: 100% Dynamical decoupling control of radical electron spins in malonic-acid crystal. Atomic-scale sensing with defect centers ----------------------------------------- - Single molecule NMR [`Nature Nanotechnology 6, 242 (2011) `_] .. figure:: ./_static/research_singleNMR.jpg :width: 500px :align: left :alt: single molecule NMR :figwidth: 100% A single nuclear spin cluster can be identified with a defect center under dynamical decoupling control.