报告人:Prof. Dr.?Jure Demsar,Institute of Physics, Johannes Gutenberg-University Mainz, Germany
时间:3月1日(周二)16:00
单位:中国科学院物理研究所
参会方式:腾讯会议
会议ID:343-280-968
摘要:
Intertwined order parameters are ubiquituos to advanced quantum solids, with the interplay between the different degrees of freedom (charge, spin, lattice) being responsible for their functional properties. Real-time femtosecond techniques?offer means to investigate the coupling strengths between the different degrees of freedoms as well as their manipulation,?that may lead to light-induced metastable states.?Charge density wave (CDW) systems present a prototype system with a coupled electronic and lattice orders, and have been extensively studied by different ultrafast spectroscopic methods.?Here, I will first focus on the order parameter dynamics in a prototype quasi one-dimensional Peierls CDW system K0.3MoO3, and address recent studies of an unconventional CDW order in BaNi2As2.
报告人简介:
Dr. Jure Demsar is a Professor of experimental solid state physics at the Johannes Gutenberg-University Mainz. His group focuses on real-time spectroscopy and manipulation of symmetry-broken ground states, using lab-based time-resolved techniques like broad-band optical spectroscopy, electron diffraction and THz spectroscopy, and is involved in experiments at large-scale facilities using intense narrow band THz excitation, time-resolved photoelectron spectroscopy, and X-ray diffraction. The group focuses on nonequilibrium phenomena in superconductors, interplay of superconductivity with competing orders, dynamics and photoinduced phase transitions in density wave systems, correlations in heavy-electron systems, optical manipulation of antiferromagnets, and has been heavily involved implementing new data-acquisition and analysis approaches in time-resolved momentum microscopy.
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报告人:James Bailey ,美国桑迪亚国家实验室
时间:3月1日(周二)21:00
单位:Matter and Radiation at Extreme (MRE)
参会方式:蔻享直播
摘要:
大约一个世纪以前,Eddington 认识到恒星物质辐射的衰减决定了像太阳这类恒星内部的温度分布。高能量密度(HED)物质的不透明度计算具有很大的挑战性,原因在于需要对部分电离原子的能级结构、状态方程和等离子体效应(如电离阈值下降和谱线展宽)有完整且精确的描述。计算中需要采用近似,因为某些情况下上亿甚至数十亿的束缚-束缚态、束缚-自由态电子跃迁都会影响高能量密度物质的不透明度。但是,恒星内部条件下的不透明度计算从未在实验室测量中校准,这是因为在过去的实验条件下创建和诊断足够大且均匀的恒星内部条件的样本极具挑战性,这限制了实验室测量行星内部不透明度方法的发展。我们用超过15年的时间建立了一个基于z装置的实验平台,并开展了电子温度
在Te=156-195 eV、密度在n = 0.7-4.0 x 1022?cm-3条件下(类似于太阳辐射和对流边界区条件)的波长可分辨的不透明度实验测量。实验结果显示,在较低的温度和密度下,模拟结果与实验数据相吻合,但在较高的温度和密度下,两者出现了显著的差异。这种差异也引出了一个问题,即我们在多大程度上理解了高能量密度等离子体中的原子行为。
行星内部不透明度的实验室测量可能有助于解决太阳模型预测和实际日震观测之间长达十年之久的差异。本次视频课将概述测量方法,测量误差的研究以及正在进行的一些实验,这些实验的目的旨在解决模型与实验数据的差异。
报告人简介:
James Bailey博士于1978年获得新墨西哥大学物理学学士学位,1984年获得加州大学欧文分校物理学博士学位。在劳伦斯利弗莫尔国家实验室物理系完成博士后研究后,James Bailey博士于1985年加入桑迪亚国家实验室脉冲功率科学理事会,他目前是桑迪亚国家实验室的杰出研究员。
James Bailey博士主要从事高能密度物理相关研究,主要关注光谱学和等离子体中原子的行为,他的研究主要包括:z箍缩辐射-流体动力学测量、细胞x射线显微术、谱线发射和吸收诊断、离子束与物质相互作用实验、用斯塔克效应(Stark effect)测量1GV/m电场,以及z箍缩x射线驱动的靶丸内爆等。近年来,他的研究重心是实验室天体物理等离子体特性。
James Bailey博士目前是美国天文学会的会士,同时他在2004年也成功当选为美国物理学会会士。他曾两次获得洛克希德·马丁诺瓦奖(Lockheed Martin NOVA award)。2016年,James Bailey博士获得了美国物理学会John Dawson等离子体物理研究卓越奖(the American Physical Society John Dawson Award for Excellence in Plasma Physics Research)。
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报告人:周海清,东南大学
时间:3月3日(周四) 9:00
单位:中科院理论物理研究所
地点:理论物理所北楼322会议室
摘要:
ep弹性散射中的宇称破坏程度可用来抽取质子的弱荷和质子的奇异形状因子,该过程中的光子-光子、光子-Z玻色子交换对宇称破坏程度均有一定程度的重要贡献。在本报告中,我们将回顾下文献中对光子-Z玻色子交换贡献的理论估算,以及该贡献对抽取质子弱荷和质子奇异形状因子的影响,然后讨论下我们对该贡献所满足的色散关系的观点。
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报告人:姚顺宇,斯坦福大学理论物理研究所
时间:3月3日(周四)10:00
单位:青年科学半月谈
参会方式:蔻享直播
摘要:
JT gravity and SYK model provide a concrete model for NAdS2/CFT1?holography. Recently, the topology change in this gravitational path integral was found to be crucial for understanding some non-perturbative aspects in this holography, which is an intrinsic quantum signature. Connected manifold, like wormhole connecting two asymptotic boundary, and even higher genus surface, was shown?to be important for blackhole information paradox, late time behavior of observables and level discreteness of boundary system. In this talk, I will briefly review these new developments, and talk about two aspect my collaborators and I worked on. (1) Factorization puzzle and half-wormhole conjecture. This involves the ensemble average in this low dimension holography and a possible scheme for non-averaged systems. (2)Explanation of subleading Weingarten coefficients in random unitary behavior of gravity and Brownian SYK. Both quantum chaos and topologically non-trivial solution plays and important role.
报告人简介:
姚顺宇,现就读于斯坦福大学理论物理研究所,导师是Stephen Shenker教授和Douglas Stanford教授。2019年本科毕业于清华大学物理系,导师是高等研究院汪忠教授。主要的研究兴趣有:(1)量子混沌,量子信息和量子引力,特别的,其中的非微扰现象和半经典路径积分。(2)开放量子系统和热化。
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报告人:陈殿勇,东南大学
时间:3月3日(周四) 10:30
单位:中科院理论物理研究所
地点:理论物理所北楼322会议室
摘要:
自2003年实验上观测到X(3872)以来,实验上观测到越来越多的新强子态。这些新强子态的性质与传统的强子有较大不同,如何解释这些新强子态是目前强子物理的研究热点。本报告结合2011年Belle合作组观测到的Zb态,到2013年BESIII和Belle观测到的Zc态以及2021年BESIII和LHCb实验组观测到Zcs态,介绍我们提出的运动学机制。
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报告人:单崇新,郑州大学
时间:3月3日(周四) 15:00
单位:北京大学物理学院
地点:物理学院中楼212大教室
摘要:
金刚石材料是自然界中最坚硬的物质,在精密加工、磨具磨料、矿山开采、石油钻探等国民经济核心领域有重要应用,被称为现在工业的"牙齿"。近年来金刚石的半导体性质吸引了人们大量的关注,作为半导体,其具有禁带宽度大(5.47 eV)、载流子迁移率高(电子迁移率可达4500 cm2V-1s-1,空穴迁移率可达3800 cm2V-1s-1)、热导率高(>2000 Wm-1K-1)、击穿电场高(>107 VIcm)等特点。由于金刚石材料具有上述优异的性质,使其成为实现下一代半导体器件的理想候选材料。本报告中将汇报金刚石的基本性质、作为半导体材料的前景、存在的主要问题,以及目前的进展等。
报告人简介:
单崇新,郑州大学物理学院教授,主要从事金刚石半导体材料与器件研究,发表学术论文300余篇,被引用11000余次。获国家杰出青年基金、长江学者特聘教授、中国青年科技奖、中组部万人计划"青年拔尖人才"、人社部"百千万人才工程"及国家有突出贡献中青年专家、全国杰出专业技术人才先进集体带头人、全国产学研合作创新奖等奖励和荣誉。
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报告人:Fuguo Xie,中国科学院上海天文台
时间:3月3日(周四) 15:30
单位:北京大学物理学院
地点:KIAA-auditorium
摘要:
Hot accretion flow is widely believed to be essential for our understanding of low-luminosity AGNs (LLAGNs) and black hole X-ray binaries (BHBs) in their hard (and quiescent) state. In this talk, I will first review the current status of accretion theory. The progresses viewed from fundamental physics perspective are angular momentum transport, turbulent heating mechanism, and outflow/wind; from accretion mode perspective include magnetic-arrested disk (MAD) and high-\dot{M} hot accretion flow. Applications of these progresses in LLAGNs and BHBs will also be addressed. More specificly, I will use both the index-lumonosity correlation and the radio-X-ray correlation as tools to probe the change in accretion mode. I will also discuss the radiative properties (efficiency and SED) of MAD.
报告人简介:
Fu-Guo Xie got his batcher degree from University of Science and Technology of China (USTC) in 2004, and got his phd from Shanghai Astronomical Observatory in 2009. He then spent two-years in KIAA-PKU as a postdoc, and from 2011 he worked in Shanghai Astronomical Observatory. He is now the professor and associated head of astrophysics division of the institute. Dr. Fu-Guo Xie mostly worked on theoretical investigations of black hole accretion, and recently also on radio morphology at galaxy-cluster scale. He is also the outstanding member of the Youth Innovation Promotion Association of CAS.
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报告人:程国传,北京国际数学研究中心
时间:3月3日(周四) 16:30
单位:北京大学物理学院
地点:物理学院南楼408
摘要:
We know from experiments that topological phases exhibit spectral phenomena which survive significant geometric deformations and require no periodicity whatsoever. Thus the interesting perturbations explore regimes that go far beyond the idealized band theory. I will gently introduce coarse geometry and index theory as the mathematical core of the topological phase idea. As examples, we can rigorously analyse quantum Hall effects on strongly curved and dislocated 2D samples, and prove that anomalous gapless boundary states appear regardless of the small-scale specifics of the sample.