Metamaterials are artificial media exhibiting wave properties beyond natural and composite materials. Since their introduction in the early 2000s, metamaterials have undergone significant development as novel wave functional materials. After two-decade’s development, metamaterials have evolved from pure wave-sustaining media to a multi-frontier research field. On the one hand, they continue to herald next-gen wave technologies. On the other hand, they have become indispensable tools for exploring many advanced topics in physics. In this talk, I will present some of our recent contributions in these two directions. The first topic is devoted to using acoustic and mechanical systems as testbeds for topological models and non-Hermitian models. Examples including a four-dimensional acoustic higher-order topological phases, a chiral-symmetric topological disclination, non-Abelian braiding of degenerate modes, and non-Hermitian morphing of topological modes. In the second topic, I will present application-oriented research that results in an active acoustic metasurface for controlling complex sound fields. This technology offers unprecedented control of multi-user, crosstalk-free acoustic communications in disorder environment by generating multiple isolated channels.
 

Dr. Guancong Ma is currently an associate professor in the Department of Physics at Hong Kong Baptist University. Dr. Ma received B.Sc. in applied physics at the South China University of Technology in 2007 and Ph.D. in physics at the Hong Kong University of Science and Technology in 2012. After that, he became a postdoc fellow at the Institute for Advanced Study and the Department of Physics at the same institution until 2017. He joined the Department of Physics at Hong Kong Baptist University in 2018. He now serves as a member of the Executive Committee of the Physics Society of Hong Kong. Dr. Ma was bestowed with the “C. N. Yang Award” in 2022 by the Association of Asia Pacific Physical Societies and the Asia Pacific Center for Theoretical Physics, and was selected as one of the “Top 10 Rising Stars in Science and Technology 2021” by the China Association for Science and Technology. Dr. Ma received the RGC Research Fellowship Award (2022). He also obtained the National Natural Science Foundation of China’s Excellent Young Scientists Scheme (Hong Kong & Macao) in 2018. Dr. Ma’s research interest is in acoustic and mechanical metamaterials. He uses these systems for studying topological physics, non-Hermitian physics, and non-Abelian phenomena. He is also interested in controlling complex wavefields using metamaterials.

Please contact phweb@ust.hk should you have questions about the talk.