Eugene Demler – ETH Zuerich
Universality of optical responses of photoexcited solids
Optical drives at terahertz and mid-infrared frequencies in quantum materials are commonly used to explore the nonlinear dynamics of collective modes in correlated many-body systems and their interplay with electromagnetic waves. Recent experiments demonstrated several surprising optical properties of transient states induced by driving, including the appearance of photo-induced edges in the reflectivity, enhancement of reflectivity, and even light amplification. I will show that many of these unusual properties can be understood from the general perspective of reflectivity from Floquet materials, in which pump-induced oscillations of a collective mode lead to parametric generation of excitation pairs. This analysis predicts a universal phase diagram of drive induced features in reflectivity, which evidence a competition between driving and dissipation. To illustrate general analysis, I will discuss applications of this formalism to several experimental systems.
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QuCoLiMaTalks are the weekly seminar of the collaborative research center TRR 306 QuCoLiMa (Quantum Cooperativity of Light and Matter).
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