This study explores how optical conductivity and magnetic circular dichroism (MCD) can be used to probe the quantum geometry and topology of the ground state in a magnetic topological insulator, MnBi₂Te₄. Using first-principles calculations and effective field theory, the researchers demonstrate that the generalized optical weight, derived from the absorptive part of optical conductivity, is directly connected to the ground state quantum geometry and topology. They show that three septuple layers of MnBi₂Te₄ exhibit enhanced MCD in a narrow infrared photon energy window, indicating a Chern insulator state. The quantum weight, which is related to the quantum metric of the occupied band manifold, is found to be significantly larger than the lower bound provided by the Chern number. The study also highlights the connection between the optical response and the quantum geometry, showing that the MCD in 3SL MnBi₂Te₄ is nearly perfect in a specific energy range. The results suggest that optical methods are powerful tools for probing the quantum geometry and topology of materials. The study provides insights into the electronic structure and optical properties of MnBi₂Te₄, and demonstrates the potential of using optical measurements to understand the quantum properties of topological insulators.This study explores how optical conductivity and magnetic circular dichroism (MCD) can be used to probe the quantum geometry and topology of the ground state in a magnetic topological insulator, MnBi₂Te₄. Using first-principles calculations and effective field theory, the researchers demonstrate that the generalized optical weight, derived from the absorptive part of optical conductivity, is directly connected to the ground state quantum geometry and topology. They show that three septuple layers of MnBi₂Te₄ exhibit enhanced MCD in a narrow infrared photon energy window, indicating a Chern insulator state. The quantum weight, which is related to the quantum metric of the occupied band manifold, is found to be significantly larger than the lower bound provided by the Chern number. The study also highlights the connection between the optical response and the quantum geometry, showing that the MCD in 3SL MnBi₂Te₄ is nearly perfect in a specific energy range. The results suggest that optical methods are powerful tools for probing the quantum geometry and topology of materials. The study provides insights into the electronic structure and optical properties of MnBi₂Te₄, and demonstrates the potential of using optical measurements to understand the quantum properties of topological insulators.