光電智能計算、二維材料、激光等離子體質子加速器、QGP整體極化 | 本週物理講座
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報告人：林效，Westlake University
時間：9月24日（週二）12:00
單位：江蘇省物理學會
鏈接：
摘要：
The interplay among frustrated lattice geometry, non-trivial band topology and correlation yields rich quantum states of matter in kagome systems. A series of recent members in this family, AV3Sb5 (A = K, Rb or Cs), exhibit a cascade of symmetry-breaking transitions, involving the 3Q chiral charge ordering, electronic nematicity, roton pair density wave and superconductivity. The nature of the superconducting order is yet to be resolved. Here we report an indication of dynamic superconducting domains with boundary supercurrents in intrinsic CsV3Sb5 flakes. The magnetic field-free superconducting diode effect is observed with polarity modulated by thermal histories, suggesting that there are dynamic superconducting order domains in a spontaneous time-reversal symmetry-breaking background. Strikingly, the critical current exhibits double-slit superconductivity interference patterns when subjected to an external magnetic field. The characteristics of the patterns are modulated by thermal cycling. These phenomena are proposed as a consequence of periodically modulated supercurrents flowing along certain domain boundaries constrained by fluxoid quantization. Our results imply a time-reversal symmetry-breaking superconducting order, opening a potential for exploring exotic physics, for example, Majorana zero modes, in this intriguing topological kagome system.
報告人簡介：
Dr. Xiao Lin received his B.S. degree from Zhejiang University (2008), and Ph.D. degree from Zhejiang University (2013). He did his postdoctoral studies at Ecole Supérieure de Physique et de Chimie Industrielles (ESPCI), Paris Tech. from 2013 to 2015. He became a Humboldt postdoctoral research fellow at Cologne University from 2016 to 2018. He joined Westlake University as assistant professor in March 2018. Dr. Lin has rich experience in studying the transport properties of quantum matter, such as polar superconductors, polar metals, chiral superconductors, etc. His current research interests focus on nonlinear optical/transport phenomena, superconducting diode effect, quantum transport and quantum phase manipulation.
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報告人：樑作堂，山東大學
時間：9月24日（週二）15:00
單位：中國科學院理論物理研究所
地點：北樓322
Zoom ID: 832 7630 0290
Passcode: 691240
摘要：
自上世紀七十年代起，高能反應實驗發現了一系列意外自旋效應，生出高能自旋物理研究方向。自旋軌道耦合是相對論運動的粒子系統中相互作用的基本特性，強相互作用中的自旋軌道耦合在高能自旋物理中起到了極其重要的作用。高能重離子碰撞過程的整體極化效應是強相互作用自旋軌道耦合的必然結果，理論預言被STAR等大型國際合作實驗所證實，爲強相互作用理論發展特別是夸克膠子等離子體(OGP)性質的研究開闢了新途徑，開啓了高能自旋物理研究新方向。本報告將簡敘自旋軌道耦合在解釋高能反應一系列意外自旋效應中的特殊作用，然後重點介紹高能重離子碰撞過程整體極化效應的基本思想、實驗驗證以及當前研究的熱點。
報告人簡介：
樑作堂，山東大學講席教授。1984年山東大學本科、1987年碩士畢業，1994年在德國柏林自由大學獲博士學位，1998年聘爲山東大學教授，2002年獲教育部跨世紀優秀人才基金資助，2005年獲國家傑出青年科學基金資助2009年聘爲長江學者獎勵計劃特聘教授，目前擔任粒子物理與粒子輻照教育部重點實驗室主任，2018年1月起聘爲講席教授。主要從事強相互作用物理理論研究，研究興趣包括高能反應過程自旋效應唯象學、核子自旋結構、碎裂過程自旋效應等,與合作者原創性地提出了高能重離子碰撞過程中整體極化效應，爲量子色動力學(QCD)相變和夸克膠子等離子體(QGP)性質的研究開闢了新途徑;該效應被重大國際合作實驗所證實，開闢了QGP自旋物理研究新領域，得到同行高度關注。
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報告人：肖明磊，中山大學
時間：9月25日（週三）10:00
單位：中國科學院理論物理研究所
地點：北樓202
摘要：
Effective operators are the building blocks of effective field theories (EFT), which describe all sorts of interactions among the low energy degrees of freedom under the symmetry constraints. Recent studies manifest the great potential of on-shell techniques for the computations related to effective operators. In this talk, I will show the basic applications of on-shell techniques, including the operator/amplitude correspondence, operator basis construction and the j-basis analysis. In particular, a systematic reduction rule for effective operators is built, which involves a thorough treatment of the field redefinition ambiguity. The rule allows for a clear organization of the results from EFT computations such as matching and running. Future studies on the amplitude construction in EFT may also be introduced.
報告人簡介：
肖明磊，主要研究方向爲高能物理理論，發表論文19篇，主持博士後面上項目1項。研究領域涵蓋粒子物理唯象學、宇宙學、量子引力的全息原理、量子信息、散射振幅與有效場論。近年來在有效場論的散射振幅方法上獲得了突破性成果，解決了有效場論算符基的冗餘問題。
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報告人：李連忠，香港大學
時間：9月25日（週三）15:00
單位：中國科學院物理研究所
地點：M樓253會議室
摘要：
在先進邏輯器件中隨着晶體管尺寸繼續縮小，源極漏極隧道效應越加明顯，晶體管柵極的可控性變弱。因此，必須減少晶體管本體的厚度以確保有效的柵極控制。如"超薄"的二維半導體等新材料引起了關注。各大半導體公司也加大這一方向的研究力度,我將對二維半導體材料與先進硅基鰭式場效晶體管(FinFET16nm, 7nm)及環繞式柵極晶體管(GAA 1nm)進行電路分析，討論在先進的技術節點中使用平面二維半導體晶體管優於Si FinFET（或GAA）的好處,包含速度更快,能耗更低等。同時，我們也將討論2D半導體在材料生長上最關鍵的缺陷問題，如何能長出高質量符合未來電子學需要的二維半導體，以及製作晶體管的幾個關鍵問題包含金屬接觸, high-k介電層等等之研究進展情況。
報告人簡介：
香港大學機械工程系未來電子講席教授,香港大學物理系禮任講席教授,香港大學微電子研究中心主任,前臺積電技術研究處處長,英國皇家化學會會士,美國化學會奈米短評(Nano Letters)副編輯。1994及1996年獲得臺灣大學化學學士(BSc)及碩士(MSc)學位。1997-2002 年間任職於臺積電資深研發工程師,2006年英國牛津大學凝態物理博士並加入新加坡南洋理工大學任助理教授,2010年任中央研究院擔任副研究員,2014年加入沙特國王科技大學,2016年升任正教授, 2017年底任臺積電技術研究處處長, 2021年加入香港大學任講席教授。研究領域爲化學氣相沉積CVD和工具設計,器件製造和集成,二維半導體材料生長(石墨烯、氮化硼、二硫化合物等)。目前擁有超過60個美國專利。2018-2023全球高被引學者; 發表>500篇論文, 引用>84000次, H指數134 (AD Sci Index)。
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報告人：董建績，華中科技大學
時間：9月25日（週三）15:10
單位：北京大學物理學院
地點：物理樓中樓212
摘要：
隨着人工智能技術的飛速發展，光計算和光子集成技術、人工智能技術相結合有望解決傳統電學計算無法解決的難題，產生顛覆性和變革性技術和應用。本報告從光計算的基本理論出發，重點介紹數字域光計算髮展動態和模擬域光計算髮展動態，以及人工智能和光計算相結合在產業化應用的前景。
報告人簡介：
董建績，華中科技大學教授、博士生導師，武漢光電國家研究中心主任助理。國家重點研發計劃首席科學家，國家傑出青年基金、國家優秀青年基金、全國百篇優秀博士學位論文獎獲得者。研究方向是集成光子學和光計算，在光電子領域主流期刊發表論文100餘篇，包括Nature Communications、Light Science & Applications、Optica等期刊，入選愛思唯爾中國高被引學者。2次獲得湖北省自然科學一等獎，1次獲得國家（研究生）教學成果二等獎。擔任期刊《Frontier of Optoelectronics》執行主編、全國智能計算標準化委員會委員、中國光學學會纖維光學與集成光學專委會常務委員，作爲發起人組織光子學公開課的光電計算專題。
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報告人：郭鈺，內蒙古大學
時間：9月26日（週四）10:00
單位：中國科學院理論物理研究所
騰訊會議號：492-378-724
摘要：
Multipartite entanglement includes not only the genuine entanglement but also the k-entanglement (k≥2). It is known that most bipartite entanglement measures have been shown to be monogamous, but the monogamy relation is involved in the bipartite entanglement measures rather than the multipartite ones. Therefore, how to explore the monogamy relation for k-entanglement becomes a basic open problem. In this talk, we introduced an axiomatic definition of the monogamy relation for the k-entanglement measure based on the coarser relation of the system partition. We also present the axiomatic definition of the complete k-entanglement measure and the associated complete monogamy relation according to the framework of the complete multipartite entanglement measure we established in [Phys. Rev. A 101, 032301 (2020)], which is shown to be an efficient tool for characterizing the multipartite quantum correlation as complementary to the monogamy relation associated with the bipartite measure. Consequently, the relation and the difference between monogamy, complete monogamy, and tightly complete monogamy are clearly depicted in light of the three types of coarser relation of the system partition. We then illustrate our approach with two classes of k-entanglement measures in detail. We find that all these k-entanglement measures are monogamous if the reduced function is strictly concave, and they are not completely monogamous, and in general they are not complete.
報告人簡介：
郭鈺，內蒙古大學數學科學學院教授、博士生導師。主要從事算子理論、算子代數與量子信息交叉領域理論研究。主持在研國家自然科學基金面上項目一項，主持完成國家自然科學基金面上項目、國家自然科學基金青年科學基金項目、中國博士後科學基金項目、山西省自然科學基金面上項目、山西省自然科學基金青年基金項目、山西省留學人員科技活動擇優資助項目、山西省高等學校科技創新項目優秀成果培育項目等項目8項。在科學出版社出版專著1部，在 Quantum、Quant. Sci. Tech.、Phys. Rev. A、New J. Phys.、J. Phys. A等雜誌發表學術論文50餘篇。
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報告人：Prof. David Andelman，Tel Aviv University
時間：9月26日（週四）16:00
單位：中國科學院理論物理研究所
地點：物理所M樓253會議室
摘要：
The Poisson-Boltzmann theory stems from the pioneering works of Debye and Onsageland is considered even today as the benchmark of ionic solutions and electrifield interfaces. lt has been instrumental during the last century in predicting charge distributions and interactions between charged surfaces, membranes, electrodes, macromolecules, and colloids. The electrostatic model of charged fluids, on which the Poisson-Boltzmann description rests and its statistical mechanical consequences have been scrutinized in areat detail. Much less, however, is understood about its probable shortcomings when dealing with various aspects of real physical, chemical, and biological systems. After reviewing the Poisson-Boltzmann theory, l will discuss several extensionsand modifications to the seminal works of Debye and Onsager as applied to ions and macromolecules in confined geometries, These novel ideas include the effect of dipolar solvent molecules, finite size of ions, ionic specificity, surface tension, and conductivity of concentrated ionic soutions.
報告人簡介：
David Andelman completed his PhD studies in Physics at MiT in 1984. Between 1984-1987 he was a joliot-Curie post-doc fellow at College de France (in the group of P.G. de Gennes) and at Exxon Research and Engineering (New Jersey). Since 1987 he has been on the faculty of the School of Physics of Tel Aviv University. His interest lies in modeling soft and biological matter within the tools of statistical physics. in recent years, he worked on charged soft matter including polyelectrolytes, ionic liguids and solutions, and charged membranes, exploring their equilibrium and electrokinetic properties.
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報告人：王強華，南京大學
時間：9月26日（週四）16:00
單位：清華大學物理系
地點：理學院鄭裕彤大講堂
摘要：
In this talk, I discuss several remarkable effects when strong electron correlations coexist with electron-phonon coupling. In high-Tc cuprates, the isotope exponent diminishes around optimum doping, but the exponent diverges positively in underdoped and overdoped regimes. We propose a two-boson model, with one of the modes being phonons, and find that the experimental anomalous isotope effect can be nicely explained if both of the boson modes are attractive for d-wave pairing. We substantiate the phenomenological model in by functional renormalization group calculations in a microscopic Hubbard model with Hubbard interaction and various types of optical phonon modes. We find all Holstein-like phonons suppress the d-wave SC, leading to negative isotope effect, while the SSH-type phonons enhance d-wave SC, leading to positive isotope exponent that diverges where Tc itself vanishes, in nice agreement with experiments. We also discuss the effect of strong electron-phonon coupling coexisting with strong electron correlations. We find a rich variety of competing orders in square lattices and Kagome lattices, with either positive or negative isotope effects, shedding lights on possible avenue in achieving higher superconducting transition temperature by utilizing electron-phonon coupling in correlated materials. Wherever applicable, the results are confirmed by quantum Monte Carlo.
報告人簡介：
王強華，2002年起任南京大學教授。從事凝聚態理論方面的研究，主要研究方向爲強關聯電子系統中的超導等物質態的物理性質及其微觀機理。提出並命名準粒子散射相干效應；提出和發展處理強關聯繫統物理的非約束及有限溫情況下的重整化平均場方法；提出和發展基於費米子雙線性散射模式分解的泛函重整化羣方案; 揭示和發現若干強關聯體系中的超導微觀機理和超導配對特性，以及其它相關磁性和拓撲物質態特性。
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報告人：遊智鴻，廈門大學
時間：9月27日（週五）10:00
單位：中國科學院物理研究所
地點：M樓255會議室
摘要：
Liquid-liquid phase separation is a fundamental process that continuously attracts attention from scientists and engineers across diverse disciplines. While the equilibrium theory is well known, the physics of LLPS in nonequilibrium environments is still at its infancy, despite its relevance to microfluidics and cellular systems. In this talk, I will show how activity, particularly active stresses and flows, can remodel the equilibrium physics of LLPS. Fundamentally, we show that activity can introduce many interesting phenomena, including the arrested phase separation, giant interfacial fluctuations, active capillary waves, and activity-induced wetting. Practically, our results offer a generic method to manipulate diverse aspects of LLPS using activity, ranging from the behavior of droplets to the kinetics, structure, and degree of phase separation. Our results highlight the rich new physics of LLPS invoked by activity.
報告人簡介：
Dr. Zhihong You is currently a professor at the Department of Physics, Xiamen University. He received his doctorate in physics from Leiden University in 2019. After that, he worked at the University of California Santa Barbara for three years as a postdoc scholar, under the supervision of Prof. M. Cristina Marchetti. In 2022, he started his own group at Xiamen University. He was awarded the National Young Talent Program, and has published in top journals including Science, Science Advances, PRX, PRL, PNAS. He is mainly interested in the theoretical aspects of active, soft&bio matter. His works involve bacterial colonies, active liquid crystals, liquid- liquid phase separation, and nonreciprocal (i.e. violating Newton's 3rd law) systems etc.
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報告人：林晨，北京大學物理學院
時間：9月27日（週五）15:00
單位：北京大學物理學院
地點：物理學院思源多功能廳（西301）
摘要：
在科研領域，激光驅動的高梯度粒子加速器和高亮度輻射源已經成爲近幾十年的研究熱點。通過超強激光脈衝與等離子體相互作用，可以激發起微米尺度的尾波場或是靜電分離場，實現高達10 GV/m到TV/m的粒子加速梯度。這種激光等離子體加速避免了真空擊穿電場的限制，爲加速器的小型化和成本降低提供了新途徑，併爲探索更高能量區域開闢了可能性。本報告將介紹北京大學團隊在激光質子加速優化，束流調控，等離子體診斷技術，以及激光質子刀建設方面的研究進展，並探討激光加速的超短束流在材料輻照、聚變能源、腫瘤放療等多領域的應用前景。
報告人簡介：
林晨，北京大學物理學院研究員，博士生導師。主要研究方向爲激光加速器和加速器控制系統。近五年來，以第一作者/通訊作者在加速器和等離子體領域主流期刊上發表論文三十餘篇，獲批專利十餘項。國家重點研發計劃課題“激光加速器控制系統研製和應用平臺建設”負責人，獲國家自然科學優秀青年基金資助，核學科女性獎，中國物理學會蔡詩東等離子體物理獎，入選ITER計劃專項物理人才項目首席科學家。
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