Time:12:10, Monday, October 13, 2025
Speaker:Prof. Yuan-Chung Cheng
              Dept. of Chemistry, NTU
Title: A Schrödinger–Langevin Framework for Open Quantum Dynamics and Ultrafast Spectroscopy of Molecular Systems
Place : R36173, 1F, Dept. of Physics, Building of Science College, NCKU


Abstract:
Open quantum system dynamics are central to understanding a wide spectrum of physical and chemical phenomena, from quantum devices to conjugated polymers and photosynthetic complexes. Developing accurate theories for such dynamics remains a formidable challenge, particularly for systems where strong electronic–vibrational couplings dominate. In this talk, I will present a Schrödinger–Langevin theoretical framework designed to address this challenge by treating electronic and nuclear motions on an equal footing. The approach provides a wave packet picture of dissipative quantum dynamics and enables direct simulation of laser-driven, nonadiabatic, and dissipative processes in molecular systems. I will demonstrate how this framework allows us to compute multidimensional spectroscopic signals, revealing distinctive spectral fingerprints of elusive quantum phenomena such as Berry phase effects and Fermi resonances. These results highlight the method’s potential as a powerful tool for pushing the frontiers of ultrafast nonlinear spectroscopy. More broadly, they emphasize the importance of dynamical representations that capture the subtle balance between quantum fluctuations and dissipation in the accurate description of open quantum systems.