相对论修正效应、高温超导长带制备、半非线性霍尔效应、量子材料集体激发 | 本周物理讲座

1Quantum dynamics in the superconducting phase

报告人：Prof. Václav Janiš，Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic

时间：5月21日（周二）10:30

单位：中国科学院物理研究所

地点：M253 会议室

摘要：

Quantum dynamics in many-body interacting systems reflects the non-commutativity of the operators of kinetic energy and particle interaction of their Hamiltonians. It is present only in theories beyond the Hartree-Fock mean-field approximation. The paradigm theory of superconductivity of Bardeen, Cooper, and Schrieffer (BCS) does not contain any quantum dynamics. One must go beyond this approximation to include quantum dynamics in superconducting materials, particularly in strongly-correlated electron systems. Dynamical extensions of the BCS theory of superconductivity suffer, however, from the discrepancy between the critical point calculated from the disordered high-temperature and ordered low-temperature phase. We present a way to correct this deficiency in a generic Hubbard model with attractive interaction.

We first analyze self-consistent dynamical approximations to show that the generic difference between the dynamical and conserving two-particle vertices is responsible for their inability to consistently match the ordered and disordered phases at the critical point. We propose a solution to this problem and show how to modify the contributions from the anomalous Green functions in the ordered phase to guarantee the order parameter's emergence at the critical point of the superconducting susceptibility from the high-temperature phase. We exemplify this construction on the Landau expansion in second-order dynamical mean-field theory.

报告人简介：

Prof. Václav Janiš, a distinguished Condensed Matter theorist and senior researcher at the Institute of Physics of the Czech Academy of Sciences, has significantly contributed to the field of non-relativistic quantum many-body theory. His extensive experience focusing on non-perturbative methods, many-body Green functions, and collective and critical phenomena of strongly correlated electrons has pushed the boundaries of knowledge. His research interests include quantum dynamics in Fermi systems with broken symmetry and long-range order, superconductivity, itinerant magnetism, charge diffusion, spin glasses, and quantum critical behavior. His research results are at the forefront of theoretical investigations in the physics of correlated electrons. https://orcid.org/0000-0001-5959-6935

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报告人：金小博，北京师范大学

时间：5月22日（周三）10:00

单位：中国科学院理论物理研究所

地点：北楼322

摘要：

在双重夸克偶素的产生过程中强子化过程发生了两次，这使得这一过程更加敏感于QCD中的非微扰效应，更有利于人们探索重夸克偶素的产生机制。我们在非相对论量子色动力学（NRQCD）的框架下，系统的研究了相对论修正效应对双重夸克偶素的强产生过程和光生过程的理论预言带来的影响。对于强产生过程，我们和LHCb实验组最新的测量数据进行了对比，发现在包含了相对论修正效应之后理论预言和实验测量的一致性大大提高。对于光生过程，我们给出了在未来的正负电子对撞机FCC-ee，CEPC和CLIC上的理论预言，此计算中我们不仅包含了相对论修正还包含了QCD修正。尽管在此过程中我们得到的截面较小，得益于未来的正负电子对撞机的高亮度，我们还是很有希望在未来的正负电子对撞机上观测到这一过程。

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报告人：周迪帆，上海大学

时间：5月22日（周三）10:00

单位：中国科学院物理研究所

地点：M253

摘要：

高温超导带材是超导电力，核聚变，超导医疗设备，磁浮轨道交通等应用的关键材料。化学法（MOD）制备高温超导带材具有成本低，成材效率高，性能调制途径多等优点，易实现厚膜化和宽带化，是工业化生产的理想工艺。报告介绍目前化学法制备高温超导带材的研究进展，以及近期在制备超导厚膜和调制钉扎性能方面取得的成果。同时介绍上海上创超导高温超导带材产业化的进程情况。

报告人简介：

周迪帆，上海大学副教授，上海市高温超导重点实验室副主任。2013年于东京海洋大学获博士学位，并于英国剑桥大学从事博士后研究，2018年作为上海市青年东方学者引进回国。长期从事高温超导材料的制备及应用相关研究。在超导领域权威杂志发表论文60余篇，并在美国应用超导会议(ASC)和欧洲应用超导会议（EUCAS）等重要国际会议上作邀请报告和口头报告多次。

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报告人：Zheng-Xin Liu，Renmin University of China

时间：5月22日（周三）15:00

单位：北京大学物理学院

地点：北京大学物理楼，西563会议室

摘要：

Spin-orbit coupled quantum magnetson the Honeycomb lattice，including the material a-RuCl3, have attracted lots of research interest due to the existence of Kitaey exchange interactions. Since most Kitaev materials exhibit long-range magnetic order at low temperatures, theoretical investigation of the effective spin models is helpful for experimental realization of exotic magnetic phases. In the first part of the talk，we will introduce the theoretical study of field induced quantum spin liquids motived by recent experiments on a-RuCl3. In the second part, after introducing recent STM data of few layered a-RuCl3, on the substrate of graphite, we will try to interpret the reduced Mott charge gap in 2- and 3-layered samples and then provide a possible explanation of the observed incommensurate charge super-modulation from the viewpoint of electric-dipole order. Our work may shed light on study of multiferroic properties of Kitaev candidate magnets.

报告人简介：

Zheng-Xin Liu obtained his Ph.D in the Hong Kong University of Science and Technology in 2010. In the following five years he worked in the Institute for Advanced Study in Tsinghua University as a post doctor and then as an associate member. He joined Renmin University of China in 2015. Dr. Liu's research area includes quantum magnetism, topological phases and symmetries in condensed matter physics. Recently, his interest is focused on quantum spin liquids in Kitaev materials and band structure of itinerant electrons in magnetically ordered systems.

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报告人：何建华，南京大学

时间：5月23日（周四）10:00

单位：中国科学院理论物理研究所

地点：南楼6620

腾讯会议号：654-517-742

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.

报告人简介：

何建华，南京大学天文与空间科学学院副教授。2006年获上海交通大学物理学学士学位。2011年获复旦大学理论物理博士学位。2011-2015年在意大利国家天文台从事博士后研究工作。2015-2018年获英国杜伦大学International Junior Research Fellowship，在杜伦大学计算宇宙学中心(ICC,Durham)从事研究工作。2018年12月获南京大学登峰B计划资助，加盟天文与空间科学学院。研究领域包括，修正引力，宇宙微波背景辐射，宇宙大尺度结构形成数值模拟，宇宙大尺度星系巡天观测。目前主要从事引力波，数值相对论，暗能量实验检测等相关研究。曾经参与欧空局Euclid卫星项目，以及由美国能源部主导的Dark Energy Spectroscopic Instrument (DESI)巡天项目。截止目前，以第一作者/通讯作者身份发表1篇Nature Physics, 1篇Nature Astronomy（2018年12月刊封面），3篇Phys.Rev.Lett。长期担任PRL，PRD，MNRAS，JCAP等期刊审稿人。

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报告人：肖聪，澳门大学

时间：5月23日（周四）15:00

单位：北京大学物理学院

地点：西563会议室

摘要：

Intrinsic time-reversal-odd nonlinear Hall effect determined solely by Bloch band geometry has attracted extensive interests since the theoretical proposal of combining it with antiferromagnetic spintronics and the experimental observations in few-layer MnBiTe4. However, possible extrinsic contributions and their interplay with the intrinsic one have not been understood. Moreover, even the concept of nonlinear “intrinsic” contribution itself is still unclear, which has led to very recent theoretical and experimental debates. I will first introduce our recent work on the scaling law for time-odd second order nonlinear transport, which provides a basic tool for data analysis in low-frequency experiments. Then I will show some new understandings on the concept of nonlinear intrinsic transport and the prediction of high-frequency isolation of intrinsic response in a specific material.

报告人简介：

肖聪，博士毕业于北京大学物理学院，师从李定平教授和马中水教授，后在UT Austin随牛谦教授做博士后，在香港大学姚望教授组做研究助理教授。2023年8月至今为澳门大学应用物理与材料工程研究院助理教授。主要从事反常热电输运、自旋相关输运，非线性输运，非线性自旋电子学，二维材料层电子学等研究。迄今作为第一作者或通讯作者发表论文30余篇，包括Physical Review Letters 8篇，Nature Communications 2篇。担任Physical Review Letters，Physical Review X，Nature Electronics, Science Advances等期刊审稿人。

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报告人：Xin Wang，中科院国家天文台

时间：5月23日（周四）15:30

单位：北京大学物理学院

地点：KIAA-Auditorium

摘要：

Using state-of-the-art reduction methods, we analyze the new JWST data acquired by the NIRISS wide-field slitless spectroscopy (WFSS) and NIRSpec multi-object spectroscopy (MOS). The cross calibration of these two complementary modes opens up key window on unbiased investigation of star formation, feedback, and ISM properties in and beyond the cosmic noon epoch. We bring forth the first spatially resolved analysis of high-redshift galaxies with JWST WFSS and measure the first gas-phase metallicity radial gradient with sub-kpc resolution at z≥3. Using the NIRSpec MOS in high-resolution gratings, we compile a large sample of 35 galaxies at z~1-9 whose [O II]λλ3726,3729 and [S II] λλ6718,6732 line doublets are well resolved to shed light upon their ISM electron density and ionization properties. The exquisite sensitivity and wavelength coverage of the NIRSpec MOS in prism mode gives us an excellent chance to identify unique spectral features in galaxies in the epoch of reionization. We discover one of the highest redshift galaxies, spectroscopically confirmed at z=8.16, with PopIII-like stellar populations. This galaxy candidate hosting the first generation stars opens up new key frontiers on galaxy evolution and stellar physics in the early Universe.

报告人简介：

Xin Wang (王鑫) is currently an Associate Professor in the School of Astronomy and Space Science, University of Chinese Academy of Sciences (UCAS). Before professorship, Xin spent three years as a postdoctoral research associate at Caltech/IPAC. Before Caltech, Xin earned his Ph.D. in Astronomy & Astrophysics from UCLA in 2019. Xin has been the PI of two medium HST programs, awarded 45 orbits of deep near-infrared slitless spectroscopy and 38 orbits of ultra-deep near-ultraviolet imaging in cycles 28 and 30, respectively. Xin is the co-I of several JWST medium/large programs, including the 591-hour pure-parallel PASSAGE program and the GLASS ERS program. Xin is selected by NASA as one of the participants in the inaugural JWST master class, and has hosted several JWST proposal planning workshops for the community, including the one held at KIAA in Dec 2019.

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报告人：郭建东, 中国科学院物理研究所

时间：5月23日（周四）16:00

单位：清华大学物理系

地点：理学院郑裕彤大讲堂

摘要：

凝聚态体系中准粒子集体激发行为的研究对理解材料新奇物理性质的形成与演变机理至关重要。表面谱学分析为相关实验观测提供高分辨率的强大方法。本报告将介绍其中的高分辨率电子能量损失谱技术，以及本小组在对表面声子、等离激元以及界面电子-晶格耦合等问题研究中取得的进展。本报告还将简要介绍新型磁性氦原子散射谱仪的研制进展。

报告人简介：

郭建东，1996年中国科技大学本科毕业，2001年中国科学院物理研究所研究生毕业，获得凝聚态物理博士学位；之后在美国田纳西大学做博士后研究；2005年获得中国科学院百人计划支持回到物理研究所工作。现任物理研究所研究员，中国科学院大学物理科学学院副院长；中国物理学会表面界面物理专业委员会主任，中国真空学会常务理事。他的研究兴趣主要在于复杂氧化物低维结构的可控制备及其中新奇物理现象的研究；曾经先后主持国家重点研发计划、国家杰出青年科学基金、国家自然科学基金重点项目、中国科学院科研仪器设备重大研制项目等。

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报告人：路建明，北京大学物理学院

时间：5月24日（周五）15:00

单位：北京大学物理学院、北京物理学会

链接：

摘要：

基于二维范德华异质结的新奇物性探索和调控已经成为凝聚态物理和材料科学等领域的前沿热点方向之一。而有序态的研究，比如局域有序的磁有序态、电荷有序态以及整体有序的拓扑物态等，不但有助于理解量子材料中的基础物理现象和规律，更是与新型电子器件和下一代量子功能器件的研制息息相关。本报告将介绍近年来原子级尺度的范德华材料及其异质结中发现的电荷极化，包括晶格驱动的铁电态、电子驱动的自发极化态，探讨多种有序态之间的紧密关联行为，并展示其在量子器件中的非易失性调控功能和广泛的应用前景。

报告人简介：

路建明，北京大学物理学院助理教授。2006年本科毕业于上海交通大学物理学系，2011年博士毕业于香港科技大学，2011—2017在香港科大、荷兰Zernike先进材料研究所、奈梅亨强磁场中心（HFML）从事博士后研究，2017年10月加入北京大学。

主要从事低维量子材料的电学输运研究，代表性研究成果包括离子液体场效应晶体管在过渡金属硫族化物中诱导伊辛超导态，石墨烯摩尔超晶格中的铁电极化，菱方石墨烯中的陈绝缘体调控。相关工作发表在Science, Nature Communications, Nano Letters等杂志上。

图片来源于：https://www.163.com/dy/article/E4SFU5H9051184SU.html

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