Title: Theoretical Spectroscopy for Driven Systems
Abstract:
Understanding and predicting ultrafast, driven phenomena and the emergence of dynamical correlations in materials require theoretical frameworks that seamlessly integrate many-body theory, real-time dynamics, and open-quantum-system approaches on femtosecond timescales. Conventional many-body diagrammatic approaches are not scalable in practice and, as such, cannot describe the dynamics of realistic systems due to the complexity of time-evolution that incorporates time-nonlocal memory effects. I will present recent developments in overcoming these problems through the real-time Dyson expansion and dissipative Lindblad–Kadanoff–Baym approaches. The new formalisms circumvent the critical bottlenecks and provide a framework for computing spectroscopic observables in driven quantum systems. These approaches provide direct access to time-dependent spectral functions, enabling the analysis of dynamical signatures induced by external driving, relaxation, and correlations induced by interactions with dissipative baths. I will exemplify this by exploring the ultrafast renormalization of electronic states and the relaxation dynamics in model semiconductors. I will then focus on the description of emergent excitonic spectral signatures. I will specifically then comment on the limitations of the diagrammatic description of exciton-exciton interactions.
Bio:
Dr. Vlcek received his PhD in 2016 jointly from The Hebrew University of Jerusalem (Israel) and University of Bayreuth (Germany), from condensed matter physics and he received Minerva Fellowship of the Max Planck society. He is an associate professor at UCSB in Materials and Chemistry departments. His research focuses on quantum many-body theory of excited state dynamics of quantum materials in and out of equilibrium. He was recognized as the Emerging Leader by the Journal of Physics: Condensed Matter and Journal of Chemical Physics, he received NSF Career award, and Sloan Fellowship.
Keywords: quantum systems out-of-equilibrium, driven phenomena, ultrafast phenomena, time resolved spectrsocopy, quantum many-body dynamics
Host: Prof. Yuan Ping