2023/10/11 信息来源： 物理学院编辑：安宁 | 责编：燕元
北京大学物理学科建立110周年学术报告会（暨北京大学物理学院学术论坛·海外校友专场）由北京大学物理学院、北京现代物理研究中心主办。北京大学物理学院学术委员会主任欧阳颀院士主持。美国罗切斯特大学光学院M. Parker Givens冠名教授、俄罗斯科学院外籍院士、美国科学促进会会士张希成博士，香港城市大学物理学系讲座教授、香港高等研究院执行院长、美国科学促进会会士王循理博士应邀主讲。
报告I：From THz Air Photonics to THz Liquid Photonics
张希成（Xi-Cheng Zhang），美国罗切斯特大学光学院M. Parker Givens冠名教授，俄罗斯科学院外籍院士，美国科学促进会会士，北京大学物理系1977级本科毕业生。
Professor Xi-Cheng Zhang, the M. Parker Givens Professor of Optics, was the Director of The Institute of Optics (2012—2017), a foremost institution in optics and optical physics research and education at the University of Rochester. Prior to joining the University of Rochester, he pioneered world-leading research in the field of ultrafast laser - based on terahertz technology and optical physics at Rensselaer Polytechnic Institute (1992—2012). At Rensselaer Polytechnic Institute, he was the Eric Jonsson Professor of Science, Acting Head at the Department of Physics, Applied Physics & Astronomy; Professor of Electrical, Computer & System, and Founding Director of the Center for THz Research. He is the co-founder of Zomega Terahertz Corp.
Professor Zhang received 29 US patents; authored and co-authored 24 books and book chapters, 350 refereed papers; delivered 500 colloquia, seminars, invited conference presentations, and 200 contributed conference talks. With a B.S. in Physics from Peking University, he earned PhD degree in Physics from Brown University, RI. He is a fellow of AAAS, APS, IEEE, Optica, and SPIE. He is elected foreign member of Russian Academy of Sciences.
Following the steady evolution of THz technology since the late 1980s, the next frontier will possibly be the era of extreme THz science, where strong THz field–matter interactions can be investigated, and nonlinear THz spectroscopy and imaging are explored. However, fully realizing these opportunities will require the development of bright, efficient THz sources. Energetic ultrashort laser pulses are widely used to generate intense broadband THz pulses via interaction with a certain target. Matter can exist in four distinct states in everyday life: solid, liquid, gas, and plasma. Three of the four states—solids, gases, and plasmas - have been used as sources of THz wave for decades; however, the use of liquids as THz wave emitters is extremely limited. We present recent progress on THz liquid photonics, which is the extension of previous study of THz air photonics. A successful investigation on THz generation from liquids will help to search the last piece of the matter-phase puzzle for THz sources.
报告II：Structure and Dynamics of Metallic Glass - Atomistic Insights from Scattering Experiments
Professor Xun-Li Wang is Executive Director of Hong Kong Institute for Advanced Study at City University of Hong Kong. Prior to coming to Hong Kong in 2012, he had worked at Oak Ridge National Laboratory in the US, rising through the ranks to Distinguished Research Staff.
Professor Wang conducts research at the interface between condensed matter physics and materials science. He applies state-of-the-art neutron and synchrotron scattering techniques to study phase transformation and deformation in advanced materials. He has also made major contributions to the development of instrumentation that has enabled seminal in situ studies.
Professor Wang received B.S. in Physics from Peking University (1985) and went to Iowa State University as a CUSPEA student, where he received a PhD in Physics (1992). He is an elected Fellow of the American Physical Society (2010), American Association for the Advancement of Science (2017), and Neutron Scattering Society of America (2020). He is a recipient of Croucher Senior Research Fellowship (2021). In 2023, he was elected International Councilor of the American Physical Society.
The structure and dynamics of glassy materials have long been identified as one of the grand scientific challenges. Glasses are obtained by rapid quenching from the liquid state, bypassing atomic ordering on cooling. Therefore, in glassy materials, there is no long-range order. However, ordered structures exist at short-range (2-5 Å), medium-range (5-20 Å), and even longer length scales. Glasses differ from their crystalline counterparts not only from the structural point of view, but also in many of the physical properties such as thermal conductivity, heat capacity, and mechanical properties. Neutron or synchrotron X-ray scattering are powerful techniques to study the structure and dynamics of materials.In this talk, I will discuss atomistic insights obtained by these advanced characterization techniques on the structure, phase transition, and phonon dynamics of metallic glass, an exotic kind of glassy material. The role of medium-range order and cluster connectivity will be highlighted.Scientific opportunities at large-scale facilities such as China Spallation Neutron Source in Dongguan will also be discussed.