讲座摘要
Elastic phonons form an excellent platform for carrying and processing information due to their unique advantages, including orders of magnitude lower phononic wavelength in comparison with photonic systems, scalability toward integrated devices, and extremely low losses. The development of phonon physics has advanced the technology in high signal-to-noise information processing, high-sensitive remote sensing, and intense wave-matter interaction for future quantum networks. Thus, in actual solid carriers with ubiquitous defects, realizing a new topological robust mode, i.e., phononic skyrmion, could lead to transformative phononic applications, especially in a generally concise configuration that can be scaled accordingly for future chip-scale technologies. Recently, the hybrid spin induced by mixed transverse–longitudinal waves, which is responsible for abnormal phenomena beyond pure transverse waves and longitudinal waves (i.e., acoustic waves), has been uncovered in the elastic phononic system. The hybrid spin can inspire strong spin-momentum locking of the elastic edge modes. However, the trivial topological invariant of the latter is not robust against defects. In this talk, I will describe how to construct a new nontrivial topological structure of ultra-broadband phononic skyrmions based on the three-dimensional hybrid spin of elastic waves. It should, however, be pointed out that the formation of phononic and photonic skyrmions comes from different spin textures, with the latter being based on transverse wave spin. In more details, I will talk about using spin angular momentum as a new degree of freedom to manipulate wave propagation. Some examples on photonic and acoustic systems generating skyrmions will be presented. I will then delineate the main part of this talk related to phononic/elastic skyrmions, and how we can use them as a powerful degree of freedom to generate more functionalities for engineering applications.
嘉宾介绍
Badreddine Assouar received his PhD degree in Materials Physics from Nancy University in France in 2001. In 2002, he became a Research Scientist at “Centre National de la Recherche Scientifique (CNRS)” in France. He obtained his habilitation to supervise research (HDR) in 2007 and became a Research Professor. In 2010, he joined Georgia Institute of Technology in USA as visiting Professor, where he spent 2 years, developing researches on metamaterials. He afterwards founded the “Acoustics Metamaterials and Phononics” group at the University of Lorraine where he is developing researches on acoustic/elastic metamaterials, metasurfaces, phononics and wave physics. He is currently a Director of Research at the CNRS. In 2024, Prof. Assouar has been elected a Fellow of the European Academy of Sciences. He is also serving as Associate Editor with Physical Review Applied since 2019.
Prof. Assouar is author or co-author of more than 150 international peer reviewed publications, in leading international journals including, Phys. Rev. Lett., Nature Communications, Nature Review Materials, Science Advances, Phys. Rev. Applied …, and more than 50 invited talks and keynotes over the world. This has led to highly recognition of his works and achievements over the past 15 years, as indicated by the high citations rate his works has collected (>10000 citations, and h-index of 57).
讲座时间：2024/12/10 14:30-16:30 (GMT+08:00)
讲座地点：东南大学机械楼南高厅
主持人：朱一凡
