Kaizhi Bai is a fourth-year doctoral student in the Department of Physics at HKU. He obtained his bachelor's degree in 2022 from USTC and subsequently joined Professor Shun-Qing Shen's group at HKU. His current research primarily focuses on the physics and distinct topological phases in topological insulator films, with a particular emphasis on half quantized Hall phases. Under Professor Shen's guidance, Kaizhi has discovered new topological phases, such as the metallic quantum anomalous Hall effect and the half quantum mirror effect in topological insulator films, in collaboration with his peers. He has significantly extended the surface states solution of topological insulators to encompass the entire spectrum, forming an exact solution for the topological insulator system. Recently, he has also linked half quantum physics to topological superconductors.