Time:　1:20pm~3:10pm, October 8 (Thursday)

Title:  Engineering Quantum Materials with the Cavity Vacuum: A First-Principles QEDFT Perspective

Speaker: Asst. Prof. I-Te Lu

Affiliation: Department of Electrophysics, National Yang Ming Chiao Tung University

Place: Science Building III SC157

Abstract:

Even without external illumination, the vacuum fluctuations of an optical cavity can reshape the ground state of a solid, offering a new route to controlling quantum materials. In this talk, I will present a first-principles framework based on quantum-electrodynamical density functional theory (QEDFT) that captures this effect in periodic systems. Starting from the Pauli–Fierz Hamiltonian in the long-wavelength limit, we incorporate electron–photon correlations into the Kohn–Sham scheme and extend density-functional perturbation theory to include photon-mediated lattice dynamics. I will show that the cavity vacuum can alter materials properties such as tune semiconductor band gaps, modify superconducting critical temperatures, and induce topological phases. These results establish QEDFT as a predictive tool for designing cavity quantum materials.