Nitrogen-vacancy (NV) centers in diamond enable non-invasive, highly sensitive measurements of magnetic and electric fields, temperature, and stress. These quantum sensors bridge fundamental physics and practical applications, reaching sensitivities that conventional techniques cannot match. In this seminar, I will show how NV magnetometry provides new insights into two distinct systems: superconductors under high pressure and magnetic thin films. Using widefield NV imaging, we study a mercury-based superconductor (Hg-1223) at 4 gigapascals, directly observing the Meissner effect and revealing local inhomogeneities. I will then demonstrate how NV sensing can map the magnetic textures of domain walls in CoFeB thin films, reconstructing their underlying magnetization patterns.

Kin On (Hoho) Ho is a TQI Postdoctoral Fellow at the University of Texas at Austin, working with Prof. Xiaoqin (Elaine) Li. He earned his BSc, MPhil, and PhD degrees from The Chinese University of Hong Kong, where he was awarded the prestigious Hong Kong PhD Fellowship. His doctoral research focused on bridging quantum optics, solid-state qubits, condensed matter physics, and high-pressure techniques. Following a postdoctoral appointment at the École Normale Supérieure Paris-Saclay as a DIM QuanTiP researcher, Hoho joined UT Austin to advance the development of quantum sensors and explore quantum materials.

His broad research interests span quantum optics, solid-state spin systems, superconductivity, magnetism, and high-pressure physics, aiming to push the frontiers of quantum materials and sensing technologies.