自旋極化量子態、精確希格斯物理、二維材料光學晶體、PT對稱全息金屬 | 本週物理講座
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報告人：René Meyer，德國維爾茲堡大學
時間：3月18日（週二）11:00
單位：中國科學院理論物理研究所
地點：北樓322
Zoom Meeting ID：895 3114 7499
Passcode：275661
摘要：
Investigations of non-hermitian quantum systems recently has drawn much interest in the field of holography and the AdS/CFT correspondence. In this talk, I will focus on non-hermiticity of the PT symmetric type and, after a short introduction into the subject, present new results for a PT symmetric system of interest in holography: I will discuss our recent investigation of the phase structure and the interaction induced quantum critical conductivity in a PT symmetric non-hermitian holographic metal. In particular, the conductivity shows interesting new features in the different phases, which are qualitatively reproduced in a PT symmetrically deformed version of Landau-Ginzburg theory. I will end up with a discussion of possible future investigations in this model.
報告人簡介：
Professor René Meyer received his Ph.D. from LMU Munich, in 2009. He conducted postdoctoral research at the University of Crete (2009-12), IPMU (2012-15) and Stony Brook U. (2015-16). Since 2016, he has been working at Julius-Maximilians-Universität Würzburg (Germany). His research primarily focuses on high-energy physics, AdS/CFT correspondence, string theory, and quantum information theory.
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報告人：陳朝宇，松山湖材料實驗室
時間：3月19日（週三）15：00
單位：北京大學物理學院
地點：北京大學物理樓，西563會議室
摘要：
報告人將重點介紹其基於先進光源開發新型自旋分辨角分辨光電子能譜(ARPES)測量技術，並利用不同自旋分辨ARPES系統的優勢在磁性和非磁材料中的自旋極化量子態調控方面的一系列工作:
1.基於超高能量分辨率的真空紫外激光光源，參與開發了首臺激光光源超高能量分辨率的自旋分辨ARPES。自旋分辨的能量分辨率達到2.5 mev，爲當時世界最佳，並應用到拓撲絕緣體表面態的自旋極化研究中，發現了表面態軌道分辨的自旋-動量鎖定機制，爲開發新型自旋極化高性能電子源提供了新思路[Nat:Commun.5，3382(2014)]。
2.將自旋分辨ARPES技術應用到非磁材料的自旋極化能帶調控中，實現了非點式對稱性增強的體態隱藏自旋極化機制，揭示了其中的自旋-動量-層鎖定機制 [PRL 127，126402(2021)]。
3.發現了一種全新的懸掛鍵表面態，並實現了隱藏自旋極化機制這一描述三維體帶自旋極化的機制向二維表面態的拓展 Adv.Mater:2411733(2024)。
4.從實驗上實現了一種室溫層狀交錯磁材料，具備品體對稱性配對的自旋-谷鎖定機制[arXiv:2407.19555(2024). Nature Physics accepted]。
報告人簡介：
陳朝宇，松山湖材料實驗室特聘研究員，博導。2013年畢業於中國科學院物理研究所，凝聚態物理博士。2013年9月至2015年2月在法國國家同步輻射中心擔任博士後。2015年3月至2018年10月在同單位擔任永久職位束線科學家，2018年10月回國加入南方科技大學，任副研究員。2022年2月起任研究員。2024年10月加入松山湖材料實驗室。長期從事量子材料的能帶調控研究和先進角分辨光電子能譜技術的開發。已發表論文100多篇，其中在Nature Physics，PRX/PRL，Nat. Commun.等高水平期刊共發表(共同)一作或通訊文章30多篇。目前主持和承擔國家自然科學基金面上項目，廣東省自然科學基金傑出青年項目，國家重點研究計劃，“廣創團隊”，“孔雀團隊”，“粵港澳聯合團隊”等課題。
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報告人：Prof. Katsuo Tsukamoto，Tohoku University/Osaka University/Nagoya University, JAPAN
時間：3月20日（週四）10：00
單位：中國科學院物理研究所
地點：M樓253會議室
摘要：
In order to understand the difference of crystal growth mechanism from solutions at various environments, high resolution in-situ methods have been developed and employed not only on the Earth but also in space at International Space Station (ISS). Growth rate of solution grown crystal in space (microgravity) has been thought to be much smaller than in normal gravity conditions because of the absence of convection and flows. However, no precise measurement has been conducted so far in space environment. We developed a special interferometer and microscopes for the space experiments, the use of which have led us to an interesting result that the growth rate of solution grown crystals is equal or even larger than those in normal gravity. This was successful because we could measure the growth rate in space as precisely as on the ground. In this talk, the results based on two different approaches, i.e., phase-shift interferometer and frequency-modulation AFM, will be presented.
報告人簡介：
Prof. Katsuo Tsukamoto，His interest covers the areas of the fundamental studies of crystal growth mechanisms from liquids, the origin of solar materials that we say “crystallization 4.6 billion years ago”, protein crystal growth and perfection of semiconductor crystals, like GaN and SiC. He has also been interesting in in-situ experiments in microgravity for more than 20 years and have done many in-situ observations of crystal growth in space using rockets and international space station. Even now, many interferometric data on the growth mechanism of protein crystals have been arriving from International Space Station at our laboratories. He is the winner of Frank Prize in 2013 that was given by International Organization of Crystal Growth.
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報告人：陳朝宇，松山湖材料實驗室
時間：3月20日（週四）10:00
單位：中國科學院物理研究所
地點：懷柔園區MA樓505會議室
騰訊會議：846-311-702
會議密碼：2025
摘要：
報告人將重點介紹其近期在交錯磁材料的自旋極化量子態研究方面的工作。交錯磁結合了反鐵磁體無淨磁矩和鐵磁體有自旋極化的特性，呈現出自旋劈裂矩，壓磁性等具備應用前景的性質，其與超導或拓撲相的共存會衍生出新的物理。當前交錯磁的實驗研究集中在三維單晶和較厚薄膜上，而上述新奇性質或物理的實現多需要層狀材料和二維超薄薄膜。基於以上需求，本團隊近期進行了以下嘗試：1.從實驗上實現了一種室溫層狀交錯磁材料，具備晶體對稱性配對的自旋-谷鎖定機制 [arXiv:2407.19555 (2024). Nature Physics accepted]。2.成功生長了層數可控的超薄MnTe薄膜，實現了單層MnTe薄膜的電子結構測量，並進一步證實了MnTe中存在自旋-谷鎖定機制。
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報告人：曾華凌，中國科學技術大學
時間：3月20日（週四）15:00
單位：北京大學物理學院
地點：物理樓西202報告廳
摘要：
近年來，隨着系列二維層狀鐵電材料的涌現，如 CuInP₂S₆、α-In₂Se₃等本徵二維鐵電體系及衆多二維堆疊鐵電體系，二維鐵電物性研究取得了長足進步，爲開發原子尺度功能電子器件提供了新機遇。在本次報告中，我們將介紹近年來二維面外鐵電物性的探索進展，並針對二維極限條件下外電場難以對鐵電極化進行均勻調控這一前沿難題，探討基於撓曲電效應的二維鐵電極化普適調控策略。具體內容包括：（1）本徵α-In₂Se₃及滑移體系1T’-ReS2中二維面外鐵電物性的實驗探索；（2）本徵及摩爾二維鐵電疇的無損可逆撓曲調控；（3）二維面外鐵電物性的潛在器件應用。
報告人簡介：
曾華凌，男，博士, 於2006年本科畢業於中國科學技術大學物理系，2011年在香港大學物理系獲得博士學位，2015年入選國家創新人才計劃青年項目加入中國科學技術大學，現爲微尺度物質科學國家研究中心教授、博士生導師，長期從事實驗凝聚態物理研究。近年來，其主要研究方向爲二維半導體物性和二維多鐵物性，在新型二維半導體中首次實現電子的谷極化，在二維極限下開展了鐵電性的實驗探索，在Nat. Nanotech.、Nat. Commun.、Phys. Rev. X/Lett.、PNAS、Adv. Mater.等國際重要學術期刊上發表多篇第一/通訊作者論文，得到了國際同行的廣泛關注和認可，目前他引共計9000餘次,單篇引用最高達4000餘次。
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報告人：Igor Kolokolov，L.D. Landau Institute of Theoretical Physics, Russian Academy of Sciences
時間：3月20日（週四）15:00
單位：中國科學院理論物理研究所
Zoom Meeting ID: 840 1973 8524
Passcode: 170096
摘要：
The talk is devoted to modern development in turbulence in effectively two-dimensional systems, which include thin layers of liquid and the Earth's atmosphere. If the system is limited in size, then in a certain range of parameters, turbulent fluctuations generate a coherent vortex flow. In other words, energy is transferred from chaotic flows to regular ones. It turns out that the structure of the resulting vortices can largely be described analytically. In addition, the very possibility of vortices depends on the ratio between relatively small dissipative constants.
報告人簡介：
Prof, Igor V. Kolokolov received his Ph.D. in Theoretical Physics in 1990 and a Doctor of Phvsicsand Mathematics degree in 1998 from the Budker Institute of Nuclear Physics, Novosibirsk, He started his career as a Leading Researcher at the same institute from 1986 to 2003. Between 1993 and 1995, he completed a Postdoctoral Fellowship at INFN, University of Milano. Italy. He ioined the Landau Institute of Theoretical Physics in Chernogolovka in2002 and held positions as deputy director (2003 -2018), acting director(2018 -2019), and has been director since 2019. He teaches at multiple institutions and has published a textbook "Mathematical Methods of Physics: Problems with Solutions" (Jenny Stanford Publishing, 2024).
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報告人：Guangxing Li，雲南大學
時間：3月20日（週四）15:30
單位：北京大學物理學院
地點：KIAA-auditorium
摘要：
Physics has been transforming our view of nature for centuries. While combining our physical knowledge with computational approaches has allowed people to model the evolution of physical systems in great detail, understanding the emergence of patterns and structures is limited in comparison. Correlations between quantities is the most dependable approach to describe the relationship between different quantities. However, toward complex patterns, searching for correlations directly is often not practical as complexity often undermines correlations. We find that the key is to search for correlations from local regions and develop a new method, the adjacent correction analysis to extract such correlations. The correlation vectors exhibit remarkably regular patterns and may often lead to the discovery of new laws. The vectors we derive are equivalence to the vector field in dynamical systems. By efficiently representing spatial patterns, our approach opens up venues for classification, prediction, parameter fitting, and forecast.
報告人簡介：
Associate Professor at Yunnan University (2018-), Postdoctoral fellow at the University of Munich, Germany (2014-2018), PhD at the Max Planck Institute for Radio Astronomy, Germany (2010-2014), Master of Astrophysics at the University of Science and Technology of China (2007-2010), Bachelor of Electronics at Peking University (2003-2007). Research areas: interstellar medium, star formation, dynamical processes in astrophysics. Dynamical systems, data representation in machine learning.
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報告人：王健，山東大學物理學院
時間：3月20日（週四）15:30
單位：中國科學院理論物理研究所
地點：北樓322
Zoom ID: 897 4904 1079
Passcode: 264559
摘要：
希格斯粒子是標準模型中非常獨特的一種粒子，它的發現標誌着標準模型的巨大成功。目前希格斯粒子與其他標準模型粒子的合係數已經測量得比較精準了。但是，希格斯粒子的自合係數還有很大誤差，目前實驗上限可以達到標準模型預言值的六倍。我們研究了一對希格斯粒子產生截面的的高階修正，得到了更準確的截面對自耦合係數的函數依賴關係，從而使得該上限大大降低。
報告人簡介：
王健，2013年在北京大學獲得博士學位，之後去德國做博士後，2019年回國，任山東大學物理學院教授，主要研究領域是微擾量子色動力學(QCD)和對撞機物理。近幾年，精確計算了強子對撞機上一對希格斯粒子產生過程的QCD次次次領頭階貢獻，得到了標準模型中頂夸克和希格斯粒子到底夸克衰變寬度的QCD次次次領頭階解析結果，系統發展了在軟共線有效理論框架下進行次領頭冪次階大對數重求和的方法。多篇論文被粒子物理領域綜述《Review of particle physics》收錄，多項研究成果被LHC實驗組分析數據時採用。
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報告人：羅濤，Hefei Institutes of Physical Science, CAS & The Key Laboratory of Atmospheric Optics, CAS
時間：3月20日（週四）16:00
單位：中國科學院理論物理研究所
Zoom Meeting ID: 840 1973 8524
Passcode: 170096
摘要：
Atmospheric optical turbulence effects on light waves are one of the key limiting factors affecting the efficiency of photoelectric systems. Currently, the characteristics of atmospheric optical turbulence in the upper troposphere and lower stratosphere are still not well understood or thoroughly studied. By integrating ground-based, radiosonde, and in-situ detection methods, observations of atmospheric optical turbulence have been conducted in typical regions of China. Based on these observations, statistical models and parameterized models of upper atmospheric optical turbulence havebeen established. Combined with a mesoscale meteorological model and a single-column meteorological model based on high-order turbulence closure, prediction models have been developed to derive the temporal and spatial distribution of optical turbulence intensity. This research provides important technical and data support for the demonstration and application of photoelectric systems in the upper atmosphere.
報告人簡介：
Dr. Tao Luo received his doctoral degree in space science from University of Science and technology of China in 2008. He is currently a professor at Hefei Institutes of Physical Science, Chinese Academy of Sciences (CAS), and the deputy director of the Key Laboratory of Atmospheric Optics, CAS. His research area includes atmospheric boundary layer process, atmospheric turbulence characteristics, and active and passive atmospheric remote sensing. He has authored more than 80 peer-reviewed papers.
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報告人：劉開輝，北京大學
時間：3月21日（週五）15:00
單位：中國科學院物理研究所
地點：M樓253會議室
摘要：
光學晶體具備實現激光頻率轉換、參量放大、信號調製、量子糾纏等關鍵功能，是激光技術和裝備的核心。二維材料具備超高非線性係數、光學性質外場易調、兼容硅基芯片等優點，是新一代光學晶體的理想備選材料。然而，二維材料的光與物質相互作用距離短，導致其非線性轉換效率極低，難以成爲真正有用的光學晶體。本報告將介紹我們在二維材料光學晶體的材料生長設計、物理理論發展、光學器件構造的一些思考和進展。發展出的轉角二維材料光學晶體有望成爲新一代光學晶體體系，開闢激光技術應用新領域。
報告人簡介：
劉開輝，北京大學博雅特聘教授，凝聚態物理與材料物理研究所所長。博士畢業於中國科學院物理研究所，目前主要從事材料物理和光譜物理研究。近年來，發表通訊作者論文包括Science 3篇、Nature 3篇、Nature子刊23篇、PRL 2篇，主編專著1部，授權國家發明專利60餘項。曾獲國家傑出青年科學基金、騰訊科學探索獎、北京市自然科學一等獎、中國物理學會胡剛復獎、日內瓦國際發明展金獎。目前擔任國家工程重點項目首席科學家、國家重點研發計劃項目首席科學家。研究成果入選2020年度中國重大技術進展、2020年中國半導體十大研究進展、2024年中關村論壇重大成果。
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