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报告人：Shuyi Liu, Fritz-Haber Institute of the Max-Planck Society, Germany
时间：12月1日（周三）16:00
腾讯会议: 711 558 038，密码: 1201
Live link:
摘要：
Recent state of-the-art experimental and theoretical studies showed that plasmonic fields can be confined to a few nanometers and even down to atomic scale. Sophisticated experiments combining scanning tunneling microscopy with local optical detection and excitation (LT-photon-STM) now allow us to directly investigate microscopic mechanisms of plasmon-driven phenomena in plasmonic nano-gaps and also to perform optical spectromicroscopy at unprecedented spatial resolution.
In this talk, I will introduce the development of our home-built LT-photon-STM and discuss our recent studies on near-field physics in the plasmonic STM junction, including some fundamental plasmon-driven processes as well as high spatial resolution Raman spectroscopy. Additionally, nano-scale resolved coherent phonon dynamics of ZnO layers will be shown.
报告人简介：
Dr. Shuyi Liu focused on studying light matter interaction and ultrafast dynamics at atomic scale and surface physics/chemistry by scanning probe microscopy. He obtained his doctoral degree in physics in 2019, by the support of Max-Planck Fellowship, under the guidance of Dr. Takashi Kumagai and Prof. Martin Wolf, at Fritz-Haber Institute of the Max-Planck Society, Germany. After his doctoral study, he worked as a postdoc researcher at the same group. As a main contributor, he developed a new low temperature scanning tunneling microscope for local optical excitation and detection in his doctoral period, which aims at performing nanoscale optical spectroscopy and investigating near field physics/chemistry on crystal surface. Except that, his research involved development/application of local work function measurements, STM action spectroscopy for tautomerization and STM hydrogen junction for atomic resolution imaging. He was also granted “Chinese Government Award for Outstanding Self Finance Students Abroad 2019”.
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报告人：Yu-An Chen、Danny Bulmash、Shangqiang Ning
时间：12月1日（周三）10:30
单位：蔻享学术
参会方式：蔻享直播
会议链接：
Title: Classification of invertible fermionic topological phases by G-crossed braided tensor category
Speaker:Yu-An Chen, University of Maryland, College Park
Time:10:30 am, December 1
The integer quantum Hall states, the quantum spin Hall insulator, and the p-wave topological superconductor each have an important place in condensed matter physics due to their quantized symmetry-protected topological invariants. These systems have a unique ground state on any closed manifold in (2+1) dimensions and are examples of 'invertible' topological phases of fermions. Here I will describe a general theory describing the universal properties of invertible phases, and classifies them based on their symmetries. This approach is 'categorical': it does not depend on microscopic models. Our theories can be considered as the symmetry-enriched Kitaev's 16-fold way. Some new applications of the theory include an interacting version of the 'tenfold way' classification of topological insulators and superconductors, and also the prediction of an interesting invertible phase.
Bio:Yu-An Chen is a Postdoctoral Researcher and condensed matter theorist at the University of Maryland. He is interested in studying topological phases of matter and quantum information. His previous work focuses on bosonization, a mapping between fermionic and bosonic systems, which is useful for quantum simulation of fermions and the construction of fermionic topological phases. This approach utilizes tools in algebraic topology. He recently studies the bosonization shadow theories of fermionic invertible topological phases using G-crossed crossed braided tensor categories, and classify all chiral phases with symmetry in (2+1)D. Yu-An Chen's research style is the hybridization of math, condensed matter, and quantum information.
Title: An algebraic description of (2+1)D fermionic symmetry-enriched topological phases
Speaker:Danny Bulmash, University of Maryland, College Park
Time:10:30 am, December 2
Abstract:The key property of fermionic topological order is that fermions can be created by local operators; any action of a global symmetry group $G_f$ must respect this property. We construct an algebraic formalism for symmetry fractionalization in fermionic symmetry-enriched topological phases (FSETs). Our formalism is similar to a bosonic theory of $G_b = G_f/Z_2^F$ symmetry fractionalization, where $Z_2^F$ is the group generated by fermion parity symmetry, but with constraints that enforce the locality of the fermion. We characterize the obstructions to and classification of fermionic symmetry fractionalization. We then algebraically describe the ‘t Hooft anomaly of an FSET, that is, the obstruction to gauging $G_f$. To do so, we first gauge fermion parity, and then find a four-step sequence of obstructions to extending $G_b$ symmetry to the parity-gauged theory. We discuss an anomaly inflow argument characterizing some anomalous (2+1)D FSETs as surface theories for (3+1)D fermionic symmetry-protected topological phases.
Bio:Danny Bulmash is currently a postdoctoral researcher at University of Maryland at College Park. He got his PhD from Stanford University in 2017. He has been working on and made important contributions to various aspects of topological phases of matter including fractions, higher-rank gauge theories, and quantum anomalies.
Title: Enforced symmetry breaking by invertible topological order
Speaker:Shangqiang Ning, Chinese University of Hong Kong
Time:10:30 am, December 6
Abstact:It is well known that two-dimensional fermionic systems with a nonzero Chern number must break the time reversal symmetry, manifested by the appearance of chiral edge modes on an open boundary. Such an incompatibility between topology and symmetry can occur more generally. We will refer to this phenomenon as enforced symmetry breaking by topological orders. In this work, we systematically study enforced breaking of a general finite group Gf by a class of topological orders, namely 0D, 1D and 2D fermionic invertible topological orders. In this talk, we will discuss a series of criteria on the existence or non-existence of enforced symmetry breaking by the fermionic invertible topological orders. Using these criteria, we discover many examples that are not known previously. We also study enforced breaking of some continuous group by 2D invertible topological orders through a different argument. For 2D systems, we define the physical quantities to describe symmetry- enriched invertible topological orders and derive some obstruction functions using both fermionic and bosonic languages. In the latter case which is done via gauging the fermion parity, we find that some obstruction functions are consequences of conditional anomalies of the bosonic symmetry-enriched topological states, with the conditions inherited from the original fermionic system.
Bio:Shangqiang Ning is now a post-doctoral fellow at the Department of physics of The Chinese University of Hong Kong. He received his BS degree at Shandong University in 2014, and then move to Tsinghua University where he received his PhD degree in 2019. He was the post-doctoral fellow from Sept, 2019 to Sept, 2021 at the Department of Physics in The University of Hong Kong. His research area focus on the symmetry and topology in strongly correlated condensed matter systems.
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报告人：Adam V. Steele，zeroK NanoTech
时间：12月1日（周三）19:00
单位：蔻享学术
参会方式：蔻享直播
会议链接：
摘要：
与传统的离子源相比，极低温铯离子源(Cs+)提供非常小的光斑尺寸、更高的亮度、更高溅射率和二次离子产量，束流也可以从pA到nA范围内设定，这些特点极大提升了FIB和SIMS设备的整体性能，从而实现了2nm高分辨率精细加工。
在本次报告中，将集中介绍新型Cs+极低温离子源 (LoTIS) FIB和SIMS的最新应用进展，包括高分辨率成像（2nm）、长焦深成像、10nm集成电路编辑操作、金膜高精度加工以及铜和钢的高晶粒成像演示。报告还将展示新型Cs+离子源高分辨率 FIB/SIMS 联用系统的最新结果，通过高分辨率 (<10 nm) 的二次离子质谱 (SIMS) 提供新的元素材料分析信息。数据结果表明，Cs+ 会产生比其他常规离子源高几个数量级的次级离子，在样品分析区域内的电流也有超过100倍提升。
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报告人：杨乐仙，清华大学
时间：12月1日（周三）20:00
单位：蔻享学术
参会方式：蔻享直播
会议链接：
摘要：
准一维量子材料由于其维度限制，表现出一系列有趣的性质，例如自发对称性破缺、谱函数的能隙及赝能隙、各类物相竞争等。尤其是其中的电荷密度波转变及Luttinger液体相受到了广泛的关注。然而，这些不再新奇的物性背后的机理却并没有被完全理解。以经典的准一维体系A0.3MoO3(A = K, Rb, Tl)为例，其中的电荷密度波转变，赝能隙，非费米液体行为等问题一直是争论的焦点。本次报告将介绍利用先进的激光角分辨光电子能谱（ARPES）及时间分辨的角分辨光电子能谱(trARPES)对经典准一维体系电子结构及超快相变过程的研究。我们发现A0.3MoO3(A = K, Rb, Tl)在电荷密度波转变温度以上的正常态的奇异行为可以用Luttinger液体理论进行描述，而电声子耦合在相变过程中起了重要的作用。此外，trARPES结果表明，由于电声子耦合，在超快时间尺度上（<100 fs）激发的非相干声子导致了激光诱导的超快电荷密度波相变，这一结果不同于常规的相干声子激发导致的电荷密度波相变。进一步在准一维体系的工作表明，抑制电荷密度波能隙需要的光激发能量远高于电子对电荷密度波凝聚能的贡献，类似于由非相干声子驱动的超导相变。
报告人简介：
杨乐仙，本科及博士毕业于复旦大学，之后在德国基尔大学从事博士后研究。2016年加入清华大学物理系。主要研究方向是利用光电子能谱研究量子材料的电子结构及新奇物性，包括关联电子体系，低维材料，拓扑量子材料等。
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报告人：赵公博，国家天文台
时间：12月1日（周三）15:00
单位：中科院高能物理所
地点：高能所主楼A214、CSNS园区A1-301
Zoom：81760591527/123456
链接：
摘要：
大规模星系巡天是研究暗能量本质等宇宙学前沿问题的关键手段之一。本报告将聚焦前沿，汇报国际大型星系巡天项目BOSS、eBOSS在宇宙学方面取得的最新研究进展。
报告人简介：
国家天文台研究员，副台长，国科大天文学系主任。主要研究方向为星系巡天宇宙学，在Nature Astronomy、PRL等期刊发表论文160余篇，他引12000余次。获得国家杰青基金资助，入选“万人计划”领军人才，获得腾讯“科学探索”奖。
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报告人：周凯，法兰克福高等研究院
时间：12月2日（周四）10:00
单位：清华大学物理系
地点：物理系三楼报告厅C302
摘要：
Inverse Problems occur in almost all research areas. Due to the indirect noisy observation or even 'ill-posedness', it's usually challenging to handle the inverse problem. In this talk I will introduce some projects that utilizing deep learning techniques for solving inverse problems in physics, especially in the context of basic research for the exploration of matter in high energy nuclear physics. Specifically I will talk about early time physics identification from heavy-ion collisions, heavy-quark potential inference from lattice measurements, spectral function reconstruction from correlator, learning Neutron Star Equation of State from observatory, and microscopic interaction modelling based on density estimation for many-body system.
报告人简介：
Dr. Kai Zhou received his B.Sc. degree in Physics from Xi'an Jiaotong University in 2009, and his PhD degree in physics from Tsinghua University (Superviser: Prof. Pengfei Zhuang) with "Wu You Xun" Honors in 2014 . Afterwards he went to Goethe University for his Postdoctoral research in the Institute for Theoretical Physics (ITP). Since 2017, he joined FIAS as Research Fellow and lead the group "Deepthinkers" focusing on Deep Learning (DL) for physics and beyond, and since 2021 he became fellow at FIAS. Dr. Zhou has a very broad interest in physics and AI/DL application in different fields, particularly developing data-driven and physics-informed deep learning methods for physics research.
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报告人：杨阳，美国加州大学洛杉矶分校
时间：12月2日（周四）11:00
单位：半导体学报
参会方式：蔻享直播
会议链接：
摘要：
在本次讲座中，我将首先概述太阳能电池材料和器件的基本原理，然后重点介绍我们课题组在有机太阳能电池（OPV）和钙钛矿太阳能电池（PVSK）领域取得的相关进展。有机半导体作为光伏材料的特点之一是其具有较窄的吸收光谱。相较于有机太阳能电池发展前期所使用的宽带隙材料，近二十年来，通过近红外有机共轭分子的设计和合成，其效率从不足5%提高到了18%以上。我将总结我们课题组从2008年以来在近红外聚合物给体材料以及非富勒烯受体材料的研究成果，特别是，Y系列非富勒烯受体材料的起源及发展。另一方面，我们课题组也重点关注于钙钛矿太阳能电池的发展。钙钛矿材料在相对较低温度下进行溶液加工时，不可避免会形成大量晶体缺陷。这些缺陷通过非辐射复合可能会导致能量损失，从而限制钙钛矿太阳能电池的性能。此外，这些缺陷是导致器件加工不稳定的根本原因，从而阻碍了钙钛矿太阳能电池的商业化进程。在本次讲座中，我将着重讲解抑制缺陷在钙钛矿晶界或表面形成的策略和相关的机理研究。最后，我将和大家分享一些如何成功做好交叉学科的心得。
报告人简介：
杨阳教授于马萨诸塞大学获得了物理和应用物理学博士学位。目前已在国际著名科技刊物上发表论文430余篇，发表论文总引用高达12万余次，H因子（H-index）166，授权国际专利30余项，并参加大会特邀报告、分会特邀报告和其它受邀报告200余场。杨阳教授的主要研究方向为太阳能电池及其它高性能半导体器件。1992年至1996年，杨阳教授以研究员身份任职于圣塔芭芭拉的UNIAX公司（现为杜邦公司），随后加入美国加州大学洛杉矶分校（UCLA）材料科学与工程系任教至今，并担任Carol and Lawrence E. Tannas Jr.讲座教授。
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报告人：孙晓明，中科院计算所
时间：12月2日（周四）14:00
单位：中国科学院理论物理研究所
参会方式：蔻享直播
会议链接：
摘要：
量子计算是一种利用了量子力学特性进行计算的新型计算模型，已经在多个计算问题上展示出了超越经典计算机的计算能力。搜索技术由于其具有广泛的应用场景，是计算机领域最重要的算法设计框架之一。Grover提出的量子搜索算法能够在无序数据库查找特定元素，其复杂性相比经典算法有开平方量级的加速。在这一报告中我们将简要回顾Grover量子算法的发展，并汇报我们最近在精确搜索、有先验知识的量子搜索算法等方面的一些工作进展
报告人简介：
孙晓明，中科院计算所研究员。主要研究领域为算法与计算复杂性、量子计算等。曾获基金委首批优青资助，入选中组部首批万人计划青年拔尖人才，中国密码学会优秀青年奖、密码创新二等奖。目前担任中国计算机学会理论专委会主任，还担任《软件学报》《计算机研究与发展》《中国科学:信息科学》《Information and Computation》《JCST》《FCS》等杂志编委或青年编委。
9Quantum information measure of space-time correlation
报告人：Xiao-Liang Qi，Stanford University
时间：12月3日（周五） 10:00
单位：中科院物理所
地点∶Rm M830, IOP-CAS
摘要：
Recent developments in quantum gravity suggests that the concept of spacetime is deeply related to quantum information. Most quantum information measures are defined for quantum states. For example, mutual information measures the correlation between two subsystems in a quantum state. It is natural to ask whether correlation in spacetime can be characterized by some generalization of mutual information. In this work, we propose a space-time generalization of mutual information. The key idea is to consider a general "quantum experiment" that measures the correlation between two space-time regions, and use the setup of hypothesis testing. We discuss various properties of the spacetime mutual information, including how it provides an upper bound for all connected correlation functions, which is a direct generalization of the similar property of ordinary mutual information.
报告人简介：
Xiao-Liang Qi is a professor of physics at Stanford University. In recent years, he has been mainly working on the relation of quantum information, quantum gravity and quantum many-body physics.
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报告人：韩涛，匹兹堡大学
时间：12月3日（周五） 10:00
单位：中科院理论物理所
地点∶理论物理所南楼6620会议室
参会方式：蔻享直播
会议链接：
摘要：
Who Ordered That? I.I. Rabi asked this question when a new particle, the muon, was discovered in 1936.
Ever since, this unexpected particle has constantly brought us more surprises, including the pion discovery, parity violation, J/psi discovery, neutrinos and flavor physics etc., opening an avenue in front of us to new physics and new technology. In this talk, I will discuss a new aspect — a high energy muon collider. Due to the recent technological breakthroughs for muon cooling, the muon collider program has regained its momentum. I will present the idea and the current status for a muon collider, and discuss the rich physics potential in exploring the physics beyond the Standard Model, for two representative scenarios: the Higgs factory for the resonant Higgs production and the multi-TeV muon collider at the energy frontier.
报告人简介：
韩涛教授从事粒子物理，高能对撞机唯像学，高能量前沿新物理的研究。他于1990年在威斯康星大学获得博士学位，现为匹兹堡大学的杰出教授，创立和领导了匹兹堡大学粒子物理、天体物理与宇宙学研究中心并担任主任。他于2003年当选为美国物理学会会士（APS Fellow）、2019年当选为美国科学促进会会士（AAAS Fellow），现任美国物理学会粒子与场论分会（APS DPF）主席，能源部-自然科学基金委高能物理顾问团（HEPAP）成员，并持目前正在进行的美国粒子物理十年规划活动（DPF Snowmass 2021）。