Research Seminars @ Illinois

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Tailored for undergraduate researchers, this calendar is a curated list of research seminars at the University of Illinois. Explore the diverse world of research and expand your knowledge through engaging sessions designed to inspire and enlighten.

To have your events added or removed from this calendar, please contact OUR at ugresearch@illinois.edu

Special Condensed Matter Special Seminar - "Tracing light: on Linear and Nonlinear Terahertz Polaritonics in Quantum Paraelectrics"

Event Type: Seminar/Symposium
Sponsor: Physics, Condensed Matter
Location: ESB 190
Date: Apr 28, 2025 12:00 pm
Speaker: Zhanybek Alpichshev, IST Austria
Contact: Stephen Bullwinkel
E-Mail: bullwink@illinois.edu
Phone: 217-333-1652
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Originating Calendar: Physics - Condensed Matter Seminar; The advancement of high-speed data processing and signal manipulation technologies has pushed the frontier into the terahertz (THz) frequency range, raising a fundamental challenge: how to efficiently control electromagnetic fields at these frequencies. This issue, often referred to as the "THz gap" in optical and electronic engineering, remains a major obstacle to practical applications. A promising strategy is to manipulate THz electromagnetic waves through polaritons—hybrid light-matter excitations—that harness the intrinsic nonlinear response of matter.

In this talk, I will introduce Quantum Paraelectric (QP) solids as a novel platform for THz phonon-polaritonics, leveraging the extreme nonlinearity of SrTiO₃ in its QP phase, which arises due to its proximity to the incipient ferroelectric state. This strong nonlinearity enables efficient self- and cross-coupling between polaritons, paving the way for all-optical, field-programmable THz polariton circuits.

In the second part of the talk, I will turn to the basic problem of linear propagation of THz electromagnetic waves in SrTiO₃ and KTaO₃. As it turns out, our experimental data challenges long-held assumptions about light propagation in dispersive dielectrics—an area considered settled since the foundational works of Lorentz, Sommerfeld, and Brillouin — bringing a fresh perspective on a fundamental problem in wave physics.

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