Spin Defects in van der Waals Materials: A Platform For Quantum Sensing

Quantum sensing and information processing rely increasingly on solid-state spin defects, which offer robust qubit candidates at room temperature. Among these, nitrogen-vacancy (NV) centers in diamond have been extensively studied, but the discovery of spin defects in two-dimensional (2D) van der Waals (vdW) materials, particularly hexagonal boron nitride (hBN), has opened new avenues for compact, scalable quantum devices. The unique 2D structure of hBN enables its integration into nanoscale devices, where spin defects like the negatively charged boron vacancy serve as optically addressable qubits with promising optically detected magnetic resonance (ODMR) properties, making them highly suitable for ambient-condition quantum sensors and information storage.

The first part of this dissertation investigates the controlled generation, characterization, and functionalization of spin defects in hBN, focusing on boron vacancy defect ensembles. Techniques such as laser writing and ion implantation are used to create these defects, while plasmonic enhancement strategies significantly improve brightness and optical visibility. Pulsed ODMR measurements are used to analyze the spin coherence properties, revealing extended coherence times crucial for high-sensitivity applications.

In the second part, we explore carbon-related defects within both hBN and boron nitride nanotubes (BNNTs), where single defects exhibit unique hyperfine interactions. By combining experimental studies with density functional theory (DFT) calculations, this work identifies the atomic structures and electronic properties of these carbon-based defects. In BNNTs, carbon-related spin defects are examined for their potential in high-resolution magnetic imaging when used in scanning probe microscopy.

This research advances our understanding of spin defects in 2D materials, laying essential groundwork for future innovations in quantum information storage, nanoscale magnetic sensing and on-chip quantum technologies.