UNDERSTANDING NANOSCALE PHYSICS BY ADVANCEMENT OF NOVEL NITROGEN-VACANCY CENTERS BASED SCANNING PROBES AND SIMULATIONS

Abstract

This thesis consists of two parts centering on understanding nanoscale material physics by technology development and simulation. In the first part, we briefly introduce the properties and applications of NV centers, then we present a cost-effective method for fabricating and characterizing a new class of durable, highly integrated scanning quantum sensors using both fiber-based and cantilever-based NV center scanning probes using nanodiamonds. The nitrogen-vacancy (NV) center is a photostable fluorescent atomic defect in diamond, exhibiting unique magneto-optic effects. Its Hamiltonian is sensitive to the local magnetic, electric field, temperature, and strain, making NV centers ideal for atomic-scale quantum sensing and various scientific and technological applications.The fiber-based NV center scanning probe is compatible with any tuning fork-based scanning probe microscope and supports multiple operational modes, including near-field excitation with far-field detection, far-field excitation with near-field detection, near-field excitation with near-field detection and far-field excitation with far-field detection. These diverse functional modes enable high-sensitivity and high-resolution quantum imaging and sensing applications, such as magnetic field imaging, electric field imaging, and thermal imaging at the nanoscale. The cantilever-based NV center scanning probe is suitable for use with any commercial cantilever-based scanning probe microscopes and it allows highly integrated microwave manipulation through metal coating. Additionally, we have developed a methodology to accurately determine the orientation of NV centers beneath the probe, establishing a foundation for utilizing these unique NV scanning probes for quantum sensing. Compared to existing fabrication methods, our method is reproducible, low-cost, and robust, offering significant advancements in NV center scanning probe technology. For the second part of thesis, we also investigated the phonon modes and manipulation methods of phonons in nanoparticles. The phonons are quasiparticles representing quantized sound waves in materials, they play a crucial role in defining the thermal, electrical, optical, and mechanical properties of materials. At the nanoscale, phonons exhibit unique behaviors due to quantum confinement effects and interactions with other quasiparticles. We investigated phonons in dumbbell-shaped Au-CdSe nanoparticles using time domain, frequency domain and eigenfrequency analyses, demonstrated an all-optical phonon mode manipulation method and explored potential chiral phonon modes in chiral gold nanocubes through FEM simulations. This research opens new avenues for manipulating material properties and enhancing device performance.