The Department of Physics is delighted to welcome Professor Stefan Rotter (Vienna University of Technology) as a Colloquium Speaker for the academic year 2025/26. Please join us to listen to Professor Rotter's seminar.
A reception will be held directly after the seminar in 8 West 3.15, where tea and coffee will be provided.
The seminar is open to anyone from the university, students are encouraged to attend.
Title
Coherent perfect absorption, transmission and emission of light
Abstract
In my talk I will present three recent works focused on the perfect absorption, transmission and emission of radiation by interferometric wave engineering. In the first case, we demonstrate that even a weakly absorbing film can be turned into a “coherent perfect absorber” by building a degenerate cavity around it [1]. This special cavity perfectly couples incoming light fields with arbitrary wavefronts into the absorber – even for the case that light is a dynamically varying speckle pattern. In the second case, we demonstrate how to construct an anti-reflection structure for a complex scattering system like a disordered medium [2]. Similar to an anti-reflection coating for conventional eye-glasses, this structure leads to perfect transmission across a strongly scattering system by perfectly suppressing any back-scattering. As I will demonstrate in the last part of my talk, these effects have a topological origin, which can be used to engineer topologically protected thermal radiation [3].
[1] Y. Slobodkin, G. Weinberg, H. Hörner, K. Pichler, S. Rotter, and O. Katz, Science 377, 995 (2022)
[2] M. Horodynski, M. Kühmayer, C. Ferise, S. Rotter, and M. Davy, Nature 607, 281 (2022)
[3] M. S. Ergoktas, A. Kecebas, K. Despotelis, S. Soleymani, G. Bakan, A. Kocabas, A. Principi, S. Rotter, S. K. Özdemir, and C. Kocabas, Science 384, 1122 (2024)
Biography
Stefan Rotter is Professor and Head of the Institute for Theoretical Physics at Vienna University of Technology (TU Wien) in Austria. After studying in Vienna and Lausanne, he held a postdoctoral position at Yale University. Since founding his research group in 2011, he has focused on non-Hermitian physics, theoretical quantum optics, and the propagation of classical and quantum waves in complex media. His group collaborates closely with experimental teams, with two joint publications being named among Physics World’s Top 10 Breakthroughs of 2022. Stefan has co-authored several widely cited review articles on wave phenomena, was selected as an outstanding referee by the APS, and has served as a guest professor at the Institut Langevin and at ENS in Paris.