量子自旋液體、統計熱力學可積性、引力波波動性、核子晶格有效場論 | 本週物理講座

我們如何理解宇宙? | 科學公開課‍

1

報告人:孫昌璞,中國工程物理研究院

時間:9月14日(週六)14:00

單位:中國科學院理論物理研究所

地點:北樓322

摘要:

基於熱力學第二定律的卡拉西奧多裡原理,引入量子熱力學可積性(QTI)的概念,爲統計力學提供了個現代基礎。在這一框架下,溫度作爲一個積分因子, 伴隨着熱力學熵衍生出來。從而基於 QTI熵可積方程(EIE),不僅可以推導出正則熱平衡態, 而且得到了偏離熱平衡的非正則態,從而揭示了有限尺寸熱力學系統和有限時間過程中信息相關性的存在,如黑洞等小系統的輻射關聯及其信息丟失現象。有限時間熱循環過程的標誌是熵產生,它導致的功率-效率約束關係, 對此我們不僅進行了系統性的實驗檢驗,而且建立了其最優調控的黎曼幾何方法。這些工作代表了我們過去二十年對統計熱力學從基礎到應用、從經典到量子、從平衡到非平衡的研究探索的系列性成果。

報告人簡介:

孫昌璞,理論物理學家,中國科學院院士,發展中國家科學院院士,中國工程物理研究院研究生院創院院長、北京計算科學研究中心講座教授。本科畢業於東北師大物理系,於南開大學獲博士學位。曾任東北師大教授,中科院理論所研究員。獲得過國家自然科學二等獎和美國1S!“經典引文獎”等獎勵以及全國先進工作者等榮譽稱號。他長期組織參與我國物理學科戰略規劃工作(基金委和科學院十三五發展規劃的秘書組組長和十四五規劃的戰略組組長),是中國物理學會副理事長,國家自然科學基金委員會監督委員會副主任,並擔任中國科學院哲學研究所學術委員會主任、北京大學物理學科卓越人才培養指導委員會主任。

他長期從事量子物理、數學物理、量子信息基礎理論的研究,其原創性的研究工作有重要國際影響。目前工作集中在複雜體系統計熱力學、能源物理和長貯裝備系統可靠性理論的研究,開展了面向國家需求的科技發展戰略研究和模式創新探索。目前他主持國家自然科學基金委員會的基礎中心項目《基礎能源物理的科學問題》。他重視青年人才的培養,連續講授高等量子力學大課多年,著有《經典楊-米爾斯場理論》和《量子力學現代教程》。他10次被評爲中科院“優秀導師”,指導的研究生有2人獲全國“百篇優秀博士學位論文”、10餘人獲得“中國科學院優秀博士論文”和中國科學院院長特別獎等。他也是人教社中學物理教材的總顧問和前言的撰寫者。

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報告人:Prof. Dr. Ulf-G. Meißner,Bonn University/Forschungszentrum Jülich

時間:9月10日(週二)15:00

單位:清華大學物理系

地點:物理樓W361

摘要:

Neutrinoless double-beta decay is one of the most interesting nuclear reactions. In this talk, I introduce Nuclear Lattice Effective Field Theory as a new tool in nuclear theory. It allows to address nuclear structure and reactions simultaneously. I show assorted results obtained so far. In particular, I will address the recent work on triton beta-decay, which is an important first step in addressing neutrinoless double-beta decay in this framework.

報告人簡介:

Prof. Dr. Ulf-G. Meißner is a full professor in theoretical physics and the leader of the theory group of the Helmholtz Institute for Radiation and Nuclear Physics at Bonn University. He is a renowned strong interaction physicist. Being the leader of a world-leading team on theoretical nuclear and hadron physics, he is the director of the Institute for Nuclear Physics-3 (IKP-3) and director of the Institute for Advanced Simulation-4 (IAS-4) at the Jülich Research Center. He was the dean of the Faculty of Natural Sciences and Mathematics, Bonn University, from 2008 to 2016. Here are a few among the many awards and honors he received: ERC Advanced Grant (2021), CAS President’s Fellowship for Distinguished Scientists (2018), Lise-Meitner Prize of the European Physical Society (2016), member of Academia Europaea (2010), Fellow of the American Physical Society (2009). He is also the Spokesperson of the Sino-German Collaborative Research Center CRC110. He has published more than 700 papers with a total citation of more than 77000 and an h-index of 115.

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報告人:同寧華,中國人民大學物理系

時間:9月11日(週三)10:00

單位:中國科學院物理研究所

地點:M830

摘要:

The projective truncation approximation (PTA) is a systematic and well-controlled method for solving the equation of motion of two-time Green's functions for many-body system. It has advantages over the conventional Tyablicov truncation sheme due to the projection idea. In this talk, I will report recent progress in the developement of PTA, including (1) H-expanded basis for describing thermal decay of particles, and (2) composite basis for describing quasi-particle interaction and collective excitation.

報告人簡介:

1997年畢業於復旦大學材料科學系;2002年在中國科學院物理研究所獲得理學博士學位;2002-2005在德國奧格斯堡、科爾斯魯厄大學做洪堡學者和博士後研究工作。2006至今在中國人民大學物理系任教。主要研究包括莫特相變、雜質量子相變等量子多體物理體系,着重發展量子多體數值方法,包括動力學平均場理論、數值重整化羣、格林函數運動方程等。已發表學術論文50餘篇。

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報告人:Yi Zhou,Institute of Physics, Chinese Academy of Sciences

時間:9月11日(週三)15:00

單位:北京大學物理學院

地點:西563會議室

摘要:

In this talk I will present our efforts to go beyond the "standard" model of the quantum spin liquid, which was formulated as a gauge theory. The new formulation is a Landau-type effective theory. Both quasiparticle-like excitations and collective modes will be discussed, as well as their physical consequences.

報告人簡介:

Yi Zhou is a professor at Institute of Physics, Chinese Academy of Sciences. He received his B.S. degree and Ph. D. in physics from Tsinghua University in 1998 and 2004 respectively. After postdoctoral journey, he became a faculty member in Zhejiang University in 2009 and moved to current position in 2019. His main research interests include quantum many-particle physics and theoretical condensed matter physics.

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報告人:Chen Yang,Scuola Normale Superiore

時間:9月12日(週四)13:30

單位:清華大學物理系

地點:物理樓W105

摘要:

I will discuss primordial universe scenarios where the inflaton is weakly coupled to a strongly-self-interacting theory, and study the imprints in cosmological correlators. There are three general scenarios for the strongly coupled sector based on its mass gap in Hubble units. I will focus on the gapless scenario, which I fully solved, and will discuss two approaches to computing its correlators: the Cosmological Bootstrap and Mellin-Barnes integration. Finally, I will compare the signals to weakly coupled scenarios and comment on the potential to distinguish them.

報告人簡介:

I’m currently a PhD student in the theoretical high-energy physics group at Scuola Normale. Previously I graduated from Fudan University in 2020 and obtained my master’s degree from the University of Amsterdam in 2022. My current research interest lies in de Sitter physics with possible applications of holography, in both mathematical and phenomenological aspects.

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報告人:孫志遠,清華大學

時間:9月12日(週四)15:00

單位:中國科學院物理研究所

地點:M樓236會議室

騰訊視頻會議號:397-806-937,密碼:240912

摘要:

The ponderomotive force is an effective static force that a particle feels in an oscillating field, whose static potential may be called the ponderomotive potential. We generalize this notion to periodically driven quantum many-body systems, and propose it as a convenient tool to engineer their non-equilibrium steady states beyond the single particle level. Applied to materials driven by light, the ponderomotive potential is intimately related to the equilibrium optical conductivity, which is enhanced close to resonances. We show that the ponderomotive potential from the incident light may be used to induce exciton condensates in semiconductors, to generate attractive interactions leading to superconductivity in certain electron-phonon systems, and to create additional free energy minima in systems with charge/spin/excitonic orders. These effects are presented with experimentally relevant parameters.

報告人簡介:

Zhiyuan Sun obtained his BS in 2012 from University of Science and Technology of China, and his PhD in 2018 from UC San Diego. He worked as a postdoctoral/associate research scientist at Columbia University during 2018~2021, and as an HQI postdoc Fellow at Harvard University during 2021~2022. Since 2022, he has been an assistant professor at the physics department of Tsinghua University. Zhiyuan works on condensed matter theory, specifically, nonequilibrium phenomena in many-body systems, light-matter interactions, and nano-optics.

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報告人:邢志忠,中國科學院高能物理研究所

時間:9月12日(週四)15:00

單位:中國科學院理論物理研究所

地點:北樓322

摘要:

Tiny neutrino masses and large lepton flavor mixing angles areexpected to originate from new physics bevond the standard mode(SM) of particle physics, but which kind of new physies is mostlikely has been an open question. This talk is intended to highlightthe canonical seesaw mechanism as a favorite, given the lessonlearnt from historical roles that lepton fayors haye plaved in thedevelopment of the SM. Some personal opinions are added on painsand gains in introducing new degrees of freedom.

報告人簡介:

邢志忠,中國科學院高能物理研究所研究員。1987年畢業於北京大學物理系,1993年獲得高能所博士學位,之後在慕尼黑大學和名古屋大學從事博士後研究,2001年入職高能所,主要研究領域爲中微子物理學。

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報告人:巖斌,IHEP, CAS

時間:9月12日(週四)15:00

單位:北京大學物理學院

地點:物理學院西B105

摘要:

The absence of signals for new heavy resonances at the Large Hadron Collider (LHC) suggests that the scale of new physics(NP) likely significantly exceeds the electroweak scale. The Standard Model Effective Field Theory(SMEFT) has become avaluable framework for systematically capturing potential NP effects, with leading contributions expected from dim-6 operators. However, chirality-flipping dim-6 operators for light fermions,which are poorly constrained as their interference with the SM will be highly suppressed. In this talk, l will discuss recent progress in exploring these NP effects through transverse polarization effects without such suppression, and it also offering a new avenue to investigate potential CP violation effects.

報告人簡介:

巖斌,2012年畢業於重慶大學物理學院,2017年獲得北京大學物理學院博士學位。2017年至2019年在美國密歇根州立大學做博士後研究員,2019年至2022年在美國洛斯阿拉莫斯國家實驗室擔任博士後研究員,並獲得 Director's Postdoctoral Fellow。2022年6月進入中國科學院高能物理研究所任副研究員,2024年獲國家自然科學基金委優青項目支持。研究方向爲 TeV 物理唯象學,具體包括希格斯和頂夸克物理,標準模型有效場論,對撞機物理等。

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報告人:Jianhua He,南京大學

時間:9月12日(週四)15:30

單位:北京大學物理學院

地點:KIAA-Auditorium

摘要:

Wave effects are a crucial aspect of gravitational waves. When the wavelength of GWs is comparable to or greater than the Schwarzschild radius of an object, the propagation of gravitational waves no longer follows geometrical optics, and coherence and interference can occur. Despite their significance, studying these wave effects can be challenging due to their complexity.

In this talk, I will discuss numerical techniques for simulating these effects in the gravitational field of a Schwarzschild black hole. I will talk about the back-scattering effect of the interaction between GWs and the background curvature. Finally, I will discuss the potential detectability of these wave effects in aLIGO.

報告人簡介:

He Jianhua is a professor at the School of Astronomy and Space Science, Nanjing University. In 2006, he received his Bachelor's degree in Physics from Shanghai Jiao Tong University. In 2011, he got his PhD in Theoretical Physics from Fudan University. From 2011 to 2015, he conducted postdoctoral research at the INAF in Italy. From 2015 to 2018, he was awarded the International Junior Research Fellowship by Durham University in the UK and worked at the Institute for Computational Cosmology (ICC, Durham) on research projects. In December 2018, he joined the School of Astronomy and Space Science of Nanjing University. His research areas include modified gravity, cosmic microwave background radiation, numerical simulations of large-scale structure formation in the universe, and observations of large-scale galaxy surveys. Currently, he is primarily engaged in research related to gravitational waves, numerical relativity, and experimental detection of dark energy. So far, he has published one paper in Nature Physics, one in Nature Astronomy (cover of the December 2018 issue), and three in Phys. Rev. Lett. as the first/corresponding author.

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報告人:何頌, 中科院理論物理研究所

時間:9月12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:

I will give an overview of the recent progress in computing and especially understanding scattering amplitudes and related quantities (such as correlation functions) in Quantum Field Theory, gravity and string theory, including all-loop geometries underlying amplitudes and correlators in maximally supersymmetric Yang-Mills theory, as well as the discovery of a combinatorial, string-like formulation for real-world scattering of colored scalars, pions and gluons.

報告人簡介:

何頌,中科院理論物理研究所研究員。長期活躍在量子場論、量子引力和絃論等高能理論前沿,近年來主要工作集中在場論、引力和絃論中的散射振幅等物理量,及其對粒子物理、引力和宇宙學乃至數學方向的應用。近年來代表性工作包括被稱爲Cachazo-何-袁體系的散射振幅新理論,與N. Arkani-Hamed合作建立的場論和絃論散射的幾何描述,以及在規範場、引力和絃論內在聯繫、量子場論和全息對偶的精確計算、數學物理等方向取得的一系列進展。

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