Speaker:
Eugene Demler – ETH Zuerich

Title:
Universality of optical responses of photoexcited solids

Abstract:
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).
The talks are given by (external) experts, whose research falls within the scope of QuCoLiMa.

More information at www.qucolima.de/talks