本周物理學術講座

2021-01-14 中國物理學會期刊網

1.新材料的計算發現:材料基因組計劃在能源和拓撲材料領域的應用

報告人:嚴琪閩,Lawrence Berkeley National Laboratory&Dept Physics

時間:2015.06.17(星期三)16:00

單位:清華大學物理系

地點:理科樓三樓報告廳(C302)

此次報告將簡略介紹材料基因組計劃(Materials Genome Initiative)在美國的發展,特別是高通量計算(high-throughput computation)和大數據(big data)技術的結合在不同的功能材料特別是能源和拓撲材料領域的應用。報告將以光催化材料的篩選和預測為例,介紹這套方法在材料發現和推廣過程中的作用。在這個方向上,我們發展了一套基於第一原理計算和數據的新材料發現方法,用以尋找小帶隙並具有合適光解水的能帶邊緣的過渡金屬氧化物。基於材料計劃(Materials Project) 的現有框架,通過使用一套新的廣泛適用的高通量自動化計算流程,我們實現了固體和表面電子結構的第一原理計算自動化。我們發現,通過高通量計算提供的海量數據與機器學習(Machine Learning)技術的結合,僅利用密度泛函水平的計算結果便可以很好的預測更高階的雜化泛函理論計算得到的半導體帶隙大小。這一發現大大加速了我們的材料篩選過程。我們使用這套發現方法成功確定了若干在光照溶液環境中穩定的光催化劑。其中兩種材料已被加州理工學院人工光合作用中心的實驗合作者成功合成,其實驗數據與我們的理論預測非常吻合。我們的研究發現了這些材料的若干共性和規律,這為繼續尋找新的光催化材料提供了理論設計的方向。報告還將簡要介紹我們使用高通量材料搜索方法在拓撲材料領域的早期工作和前景展望。

2.複雜網絡節點層次與鏈路預測

報告人:馮旭,北京航空航天大學

時間:2015.06.16 (星期二)10:00

單位:中科院理論物理研究所

地點:新樓6420會議室

將系統刻畫成複雜網絡來進行研究的方法在近年來得到迅速發展,而無處不在的網絡數據成為計算機、統計物理、社會科學以及生物等領域交叉研究的熱點。現實中的複雜網絡經常展現出層次組織的特性,而節點間連結關係的產生亦受到節點潛在層次屬性的影響。因此,利用已知網絡推斷層次結構,繼而將其應用到鏈路預測任務具有重要的實際意義。本文中,我們首先對複雜網絡中節點層次相關的研究工作進行介紹。針對已有方法中存在的一些問題,提出一個有向網絡中的啟發式節點層次度量算法,並從層次與網絡一致性以及層次在鏈路方向預測中的應用兩方面對算法效果進行討論。

3.AMS-02正負電子、反質子數據的解讀

報告人:馮磊,紫金山天文臺

時間:2015.06.16 (星期二)15:30

單位:中科院理論物理研究所

地點:新樓6420會議室

詳細解讀AMS-02正負電子、反質子數據以及討論可能的物理解釋。

4.Massless Mode and Positivity Violation in Hot QCD

報告人:蘇楠,法蘭克福大學

時間:2015.06.17 (星期三)10:00

單位:清華大學物理系

地點:理科樓三樓報告廳(C302)

Since the start of the ultra-relativistic heavy-ion collisions at RHIC (BNL) and most recently at LHC (CERN), the study of matter under extreme conditions has entered an unprecedented era. The primary goal of the heavy-ion program is to create and study a novel state of matter, namely the quark-gluon plasma (QGP), by smashing high energetic nuclei. Strikingly, the QGP created in experiments behaves like a strongly coupled liquid characterized by a tiny shear viscosity, rather than a weakly coupled gas as predicted by the fundamental theory QCD. To reconcile this apparent conflict between theory and experiment has been a key open question in the community since 15 years. In this talk, I will first give a heuristic introduction to this question. Then I will report a recent discovery of a novel massless collective excitation in the non-Abelian plasma which may provide a crucial ingredient in resolving this conflict. This new mode is generated by the confining (chromo) agnetic scale g^2T at high temperature, and it consequently induces positivity violation in the corresponding thermal spectral functions. This demonstrates the profound impact of confinement effects on collective excitations of the QGP, which manifest genuine long-range correlations that is necessary in rendering the system strongly coupled.

5.A Non-Compact Braneworld In String Theory

報告人:C.N. Pope,Texas A&M University

時間:2015.06.17(星期三)10:30

單位:北京師範大學

地點:物理樓106

We present a braneworld model within the framework of string theory in which the four-dimensional spacetime is associated with a wrapped 5-brane. Although the transverse space includes a non-compact hyperbolic 3-space, gravity is nonetheless localised on the brane, with a mass gap separating the massless graviton from a continuum of massive spin-2 states. The model evades some previous "no-go theorems" for braneworld models in string theory.

6.Nanowire spin-orbit qubits——Electric-dipole spin resonance and anisotropic exchange coupling

報告人:遊建強,北京計算科學研究中心

時間:2015.06.17(星期三)15:30

單位:北京師範大學

地點:物理樓106

A semiconductor nanowire quantum dot with strong spin-orbit coupling (SOC) can be used to achieve a spin-orbit qubit. In contrast to a spin qubit, the spin-orbit qubit can respond to an external a.c. electric field, an effect called electric-dipole spin resonance. Here we develop a theory that can be applied in the strong SOC regime. We find that there is an optimal SOC strength, where the Rabi frequency induced by the a.c. electric field becomes maximal. Also, we show that both the level spacing and the Rabi frequency of the spin-orbit qubit have periodic responses to the direction of the external static magnetic field. These responses can be used to determine the SOC in the nanowire. In addition, our study is extended to a semiconductor nanowire double quantum dot with strong SOC. We show that both spin-conserved and spin-flipped tunnelings exist and they can compete with each other when increasing the SOC. Moreover, strong Coulomb repulsion in the nanowire double quantum dot can be combined with the SOC-dependent tunnelings to yield an anisotropic exchange coupling between the two spin-orbit qubits. Furthermore, we give an explicit physical picture for this anisotropic exchange coupling.

7.The Higgs as seen from Sydney

報告人:Archil Kobakhidze,雪梨大學

時間:2015.06.17(星期三)15:30

單位:中科院理論物理研究所

地點:新樓6420會議室

The discovery of the 125 GeV Higgs boson at the Large Hadron Collider was a huge leap in our understanding of the origin of mass. I will discuss various implications of this discovery for the Standard Model, beyond the Standard Model physics and cosmology.

8.The Hunt for the Rest of the Higgs Bosons

報告人:Hao Zhang,University of California,anta Barbara

時間:2015.06.17(星期三)16:00

單位:清華大學物理系

地點:理科樓一樓會議室(C109)

We assess the current state of searches at the LHC for additional Higgs bosons in light of both direct limits and indirect bounds coming from coupling measurements of the Standard Model-like Higgs boson. Given current constraints, we identify and study three LHC searches that are critical components of a comprehensive program to investigate extended electroweak symmetry breaking sectors: production of a heavy scalar or pseudoscalar with decay to t\bar{t}; b\bar{b} and t\bar{t} associated production of a heavy scalar or pseudoscalar with decay to invisible final states; and t\bar{b} (\bar{t}b) associated production of a charged Higgs with decay to \bar{t}b (t\bar{b}). Systematic experimental searches in these channels would contribute to robust coverage of the possible single production modes of additional heavy Higgs bosons.

9.Some novel effects in two-dimensional layered materials

報告人:Qingming Zhang,Renmin University

時間:2015.06.17(星期三)16:00

單位:北京大學量子材料科學中心

地點:物理樓西563

In this talk, I will introduce two pieces of work in two-dimensional layered materials done in our group. In the first work, we report an unusual valley polarization (VP) up to 70% for B exciton in monolayer MoSe2, while that for A exciton is less than 3%, and a small but finite negative VP for A- trion. These results reveal several new intra- and inter-valley scattering processes which significantly affect valley polarization. Another one is the observation of an ultralow-frequency collective compression mode (CCM) in atomically thin black phosphorus (BP). This novel CCM indicates an unusually strong interlayer coupling in BP, which is quantitatively supported by a phonon frequency analysis and first-principles calculations. The CCM and another branch of low-frequency Raman modes shift sensitively with changing number of layers, allowing an accurate determination of the thickness up to tens of atomic layers.

10.Classification of symmetry protected topological phases with reflection symmetry

報告人:Tsuneya Yoshida,RIKEN,apan

時間:2015.06.18(星期四)10:00

單位:中科院物理研究所

地點:M830會議室

In this decade, realization of topologically nontrivial band insulators has been reported for various number of materials. In addition to this, recently, this nontrivial phase is generalized to correlated sys-tems including spin and bosonic systems. Such phases are called as symmetry protected topological (SPT) phases. Most of them are protected by local symmetry, such as time-reversal symmetry. How-ever, after discovery of a topological crystalline insulator in SnTe, it became clear that spatial symmetries can protect topological structures. Thus, we can expect SPT phases protected by spatial symmetry.

In this talk, employing a classification scheme based on the Chern-Simons theory, we classify SPT phases protected by reflection symmetry. Besides, we propose a spin model which shows non-trivial phase protected by reflection symmetry. This is a bosonic extension of topological crystal-line insulators. In study of fermionic systems, we elucidate that correlation effects can reduce the to-pological classification. As an example, we see Z classification for free-fermion systems reduced to Z4 in the presence of correlation effects.

11.Electron-phonon interaction and magneto-optical effect in topological valleytronic materials

報告人:Zhou Li,RIKEN

時間:2015.06.18(星期四)10:00

單位:中科院物理研究所

地點:M樓253會議室

In Graphene and topological insulators (recently also in Weyl semimetals), the Hamiltonian is governed by Dirac equation. In spintronics the Hamiltonian is similar but with the strength of Fermi velocity to be much smaller, making the system cross over from Dirac fermions to Schrodinger fermions. Strong distortion of the Fermi surface could introduce a hexagonal warping term in the Hamiltonian in which the energy is proportional to the cubic of the momentum. Optical and magneto-optical measurements play an important rule in determining the physics of superconductors and now we use these tools to probe topological materials. Finally the impact of electron-phonon interaction on these systems will be addressed.

12.Revealing the mysteries behind galaxy formation feedback using Bayesian computation and back-of-envelope calculation

報告人:Yu Lu,Carnegie Observatories

時間:2015.06.18(星期四)13:30

單位:清華大學物理系

地點:理科樓C302

Feedback is thought to be important in shaping galaxies, but how it works is still poorly understood. In this talk, I will present a series of studies using Bayesian computation and analytical calculations to gain insight into feedback processes in galaxy formation. In particular, I will highlight how a family of model that captures the preventive nature of feedback reproduces remarkably well a number of observational scaling relations of low-mass galaxies and discuss the implications.

13.Topological Kondo insulators and Topological Crystalline Kondo Insulator

報告人:Kai Sun,University of Michigan,Ann Arbor

時間:2015.06.18(星期四)16:00

單位:北京大學量子材料科學中心

地點:物理樓西563

In the study of strongly-correlated insulators, a long-standing puzzle remained open for over 40 years. Some Kondo insulators (or mixed-valent insulators) display strange electrical transport that cannot be understood if one assumes that it is governed by the three-dimensional bulk. In this talk, I show that some 3D Kondo insulators have the right ingredients to be topological insulators, which we called 「topological Kondo insulators」. For a topological Kondo insulator, the low-temperature transport is dominated by the 2D surface rather than the 3D bulk, because the bulk of this material is an insulator while its surface is a topologically-protected 2D metal. This theoretical picture offers a natural explanation for the long-standing puzzle mentioned above. In addition, we also find that Kondo insulators can support another type of nontrivial topological structure protected by lattice symmetries, which we called 「topological crystalline Kondo insulators」. In particular, we predict that SmB$_6$ is both a topological Kondo insulator and a topological crystalline Kondo insulator and I will also discuss recent experiments, which reveal the surface states in SmB$_6$.

14.High duty-cycle time-series photometric observations in multiple colors for asteroseismology from Dome A, Antarctica

報告人:Jianning Fu,Beijing Normal University

時間:2015.06.18 (星期四)16:00

單位:北京大學科維理天文與天體物理研究所

地點:KIAA-PKU Auditorium

High duty-cycle time-series photometric observations in multiple colors are very important for asteroseismology, since the behaviors of the pulsating stars in different colors are helpful to make mode identifications. However, the space missions including CoRot and Kepler are not able to provide light curves in multiple colors simultaneously.In this colloquium, I shall introduce our efforts in this direction with the data collected from Dome A of Antarctica. The light curves in SDSS g and r for HD 92277 observed with CSTAR in 2009 help to not only discovering the star as a new δ Scuti star with detection of multiple frequencies of pulsation but also identifying the mode of the dominant frequency. The observations with CSTAR are also used to analyze the pulsations of 4 RR Lyrae stars, including getting the properties of the Blazhko effect of 3 of them. Observations in SDSS i for an eclipsing binary with the AST3-1 in 2012 are combined with the data in Johnson I obtained with OGLE survey in 2006 to get the photometric solution of the binary system and detect the activities of spots on the surface of a component.

單擊左下角「閱讀原文」查看更多報告信息。

關注請加微信號:中國物理學會期刊網


長按二維碼,自動識別,添加關注

相關焦點

  • 從電子結構看強關聯電子體系的共性本周物理學術講座
    對於d電子體系, 這一競爭又集中表現為所謂Mott物理, 如銅氧化物高溫超導就可認為由載流子摻雜的Mott絕緣體而來。而通過電子摻雜具有強自旋軌道耦合的5d電子Mott絕緣體, Sr2IrO4, 我們用掃瞄隧道顯微鏡(STM), 發現了該體系存在50K左右的高溫超導的跡象。
  • 崔琦講座在物理研究所啟動(圖)
    崔琦講座在物理研究所啟動    中科院物理研究所於近日邀請國際知名物理學家Nai-Phuan Ong來所做學術報告,「崔琦講座」正式啟動。    崔琦是1998年諾貝爾物理獎得主,美國普林斯頓大學教授。他曾在2003年12月訪問物理所時與王恩哥所長討論了研究所的國際評價機制和高水平人才培養等問題,並表達了對中國的物理事業和中科院物理所的發展寄予的深厚期望,他表示今後會更加關心物理所的發展,為培養一批傑出的中國青年物理人才盡更大努力。
  • 本周講座信息
    主要社會學術兼職:中國光學學會理事,中國兵工學會理事,中國兵工學會光學專業委員會副主任,中國儀器儀表學會光機電及系統集成技術分會副理事長。   在國內外學術刊物或會議發表學術論文300餘篇(260餘篇被SCI、EI收錄),申請國家發明專利30餘項,已授權10餘項,獲部級科技進步三等獎一項。目前主持國家自然科學基金重點基金、863、國防預研以及橫向科研項目10餘項。指導的博士生以「太赫茲波位相成像」為題獲得2011年度全國優秀博士學位論文和2010年度北京市優秀博士學位論文。
  • 地震原理新論本周物理學術講座
    The Leptonic Dirac CP Phase from Residual Symmetry and Muon Decay at Rest Experiment報告人:葛韶鋒, Max Planck Institute for Nuclear Physics時間: 7月25日(周一)10:00單位:中國科學院高能物理研究所
  • 自旋三重態超導理論入門本周物理學術講座
    報告人:金彪,中國科學院大學時間: 7月19日(周二)14:00單位:中科院物理研究所地點:M234報告廳對自旋三重態超導的理論描述,要比自旋單態情況更為複雜。 在本講座中,將介紹自旋三重態超導微觀理論的基礎部分, 可當做對國科大開設的《固體理論》課程中超導理論部分的後繼內容。希望同學們預習好BCS 超導理論。
  • 華南理工大學「氣體物理吸附理論」技術講座
    近日,美國麥克儀器公司在華南理工大學成功舉辦了題為「氣體物理吸附理論」的技術講座,吸引了50餘位華南理工大學化學與化工學院的老師和同學積極參與。   此次技術講座由美國麥克儀器公司市場應用部經理鍾華博士主講,她首先通過一幅幅生動形象的圖片,深入淺出地介紹了物理吸附的一些基本理論和應用知識
  • 聲子晶體材料:從聲石墨烯到聲拓撲絕緣體 I 本周物理學講座
    單位:清華大學地點:理科樓鄭裕彤講堂眾所周知,材料的物理性能不僅取決於材料的組分,還決定於材料的顯微組織。為了能夠讓大家更詳細的了解WITec 300R拉曼光譜儀的功能,更好的掌握並充分利用這一設備開展相關科研工作,解決用戶使用過程中的問題,拉曼實驗室邀請WITec中國子公司的應用工程師胡海龍博士為用戶提供講座。
  • 自旋電子學材料、物理與器件研究進展 | 本周物理學講座
    報告人:韓秀峰,中科院物理研究所時間:2月28日(周四)18:30單位:中國科學院大學地點:雁棲湖校區 教1-109自旋電子學是基於電子的自旋、軌道和點和自由度,研究電子自旋相關輸運性質及自旋與磁、光、電、力 、熱、聲等物理場之間相互作用的新興學科。
  • 講座預覽||下周!超多學術大牛!
    講座預覽||下周!超多學術大牛!繽紛多彩的講座是大學最顯著的特徵,也是了解一所大學的窗口。國科大官微每周五推送的「講座預覽」欄目,將與UCASer共同分享一周講座的亮點。
  • 物理伯苓班參加中國物理學會2018年秋季學術會議
    南開新聞網訊(通訊員 餘華)近日,2017級物理伯苓班同學赴大連理工大學參加中國物理學會2018年秋季學術會議,學生們觀摩了大會邀請報告、分會場專題報告、海報展示和相關期刊投稿講座等活動,與參會師生進行了熱烈的學術討論和交流。此次活動旨在拓展學生科研視野,為物理伯苓班同學在二年級時選擇國內外科研導師創造條件。
  • 【學術講座】韓國科學技術院Ringi Kim講座通知
    報告題目:圖的星圖染色報告人:Ringi Kim講座時間:2018年>5月20日17:05講座地點:國際會議中心第一會議室邀請人:李斌龍副教授承辦學院:理學院B》,《J.Graph Theory》等國際著名SCI期刊發表多篇學術論文。
  • 熱電材料的歷史、現狀與我們這一代的使命 | 本周物理學術講座
    報告人: Qiangfei Xia,University of Massachusetts Amherst時間:4月10日(周二)15:00單位:北京師範大學物理系地點:物理樓105Developing electronics beyond Moore’s Law requires revolutionary vision
  • 學術報告邀請:神經康復中的物理療法評定與治療
    尊敬的各位同道:      茲定於10月18日(周二)晚18:30在寧波衛生職業技術學院綜合樓4樓學術報告廳舉行學術講座,誠邀您參加
  • 非常規高溫超導機理的突破口 | 本周物理學講座
    報告人:胡江平,中國科學院物理研究所時間:5月16日(周四)16:00單位:清華大學地點:理科樓鄭裕彤講堂至今距銅基高溫超導體的發現已經過去了30多年,鐵基高溫超導研究也已經有十個年頭,但是高溫超導機理依舊是凝聚態物理研究前沿的一個難題。
  • 美國物理教授情鍾弈林 伍法嶽教授講棋北師大(圖)
    美國物理伍法嶽教授在講棋  午報訊(記者張 展)本周,美國波士頓大學物理教授、世界知名科學家伍法嶽教授在北京師範大學進行了一場象棋講座,受到師大師生和京城象棋名家的歡迎。  伍法嶽教授1932年1月出生於湖南長沙,1949年隨父母赴臺灣,同年夏考入臺灣左營海軍機械學校,1955年被選派至美國舊金山學習雷達工程,返臺後在海軍軍官學校任教官;1957年考取臺灣清華大學研究所第二屆研究生,1959年9獲獎學金赴美國,入聖路易城的華盛頓大學攻讀物理,1967年開始在波士頓東北大學任教,歷任物理系助教授、副教授、教授、傑出教授及Mattheus傑出教授。
  • 西安光機所舉辦Web of Knowledge學術資源整合平臺講座
    為了讓科研人員更有效、全面地利用與自己研究領域相關的學術成果,發現新的學術空白點、增長點、推動科技創新,6月2日上午,中科院西安光學精密機械研究所舉辦了Web of Knowledge學術資源整合平臺講座。
  • 中國物理學會2005年秋季學術會議在漢圓滿落幕
    中國物理學會2005秋季學術會議於9月18~20日在武漢召開。該會議作為「世界物理年」的重要學術活動,由中國物理學會主辦,中國科學院武漢物理與數學研究所和武漢大學共同承辦。會議匯聚了全國物理學界近千名學者,還特別邀請了歐洲物理學會主席以及部分海外華人物理學家參加。
  • 學術講座丨體育科學領域英文論文的選題與規範
    為提高體育與運動醫學相關領域青年學者的英文學術論文撰寫水平和投稿規範,《運動醫學與健康科學(英文)》(Sports Medicine
  • 準實驗研究法教學學術研修班講座在線舉辦
    2020年12月10日,中國海洋大學教學支持中心與青島大學教師發展中心、青島科技大學教師教學發展中心等聯合舉辦教學學術研修班第6講,邀請北京大學教育學院博士後
  • 【直播預告】卡弗裡理論科學研究所學術講座 | 主講人:史丹福大學祁曉亮博士
    更多精彩視頻登陸網站www.koushare.com課程直播二維碼此次講座由中科院大學卡弗裡理論科學研究所主辦,授權蔻享學術進行網絡直播與錄播。廣大科研工作者可以關注「蔻享學術」公眾號,通過「視頻」»「學術直播間」欄目免費觀看。