笼目晶体、镍基高温超导体、分数量子反常霍尔效应、原初黑洞 | 本周物理讲座

1

报告人：Albert Escrivà，Nagoya University

时间：6月3日（周二）10:30

单位：中国科学院理论物理研究所

地点：北楼322

摘要：

Simulations of primordial black hole (PBH) formation are crucial for understanding the initial conditions that lead to black hole formation and for studying their properties and cosmological impact. Recently, a class of curvature perturbations known as type-II fluctuations, characterised by a non-monotonic areal radius, has attracted growing interest. However, when simulating PBH formation from type-II fluctuations using the standard Misner-Sharp approach, the evolution equations contain divergent terms (of the form 0/0), which hinder numerical progress and make the simulation impossible. In this talk, I will present a new methodology with the Misner-Sharp formalism that enables simulations of PBH formation from generic curvature fluctuations while avoiding the divergences associated with type-II curvature profiles. With the new method, we systematically study the black hole formation threshold across various fluctuation profiles and find that, for sufficiently large curvatures in the linear component of the compaction function shape around its peak, the threshold generally lies deep within the type-II regime. Furthermore, I will present an analytical formula that estimates the threshold in these cases.

报告人简介：

Albert Escrivà received his Ph.D. from the University of Barcelona and is currently an Assistant Professor at Nagoya University. His research focuses on Primordial Black Holes, particularly their formation through relativistic numerical simulations. Previously, he held postdoctoral positions at the National Astronomical Observatory of Japan (NAOJ) in Tokyo, was a JSPS Fellow at Nagoya University, and conducted postdoctoral research at the Université Libre de Bruxelles.

2

报告人：Alessandro Bombardi，Diamond Light Source

时间：6月4日（周三）14:00

单位：中国科学院物理研究所

地点：M楼249会议室

摘要：

Synchrotron light enables precise generation, control, and analysis of photon polarization across a wide energy range. This capability selectively enhances elements of the light-matter cross-section, benefiting diverse synchrotron techniques probing materials at various scales. While dominant X-ray diffraction terms preserve photon polarization, resonant conditions or advanced scattering models reveal systematic polarization modification of diffracted photons. Analyzing this final polarization distinguishes scattering processes and accesses distinct system properties. Consequently, X-ray polarization analysis investigates magnetic/chiral order, and, combined with synchrotron spatial resolution, maps domains. This approach extends to excitations involving energy/momentum transfer. Similarly, polarized-light-excited photoelectrons probe nanoscale topological magnetic textures and domains in quantum materials, complementing diffraction resolution. In this talk, I will introduce polarized light for investigating chirality and non-collinear magnetic order, discussing its key opportunities.

报告人简介：

Alessandro Bombardi is the principal beamline scientist at the I16 Material and magnetism at Diamond, the first operational beamline at Diamond that he contributed to build. Prior to this position, Alessandro was Senior Beamline Scientist, Diamond Research Fellow and visiting lecturer at Oxford University. Alessandro started his scientific career with a PhD on actinides with Prof. Gerry Lander, and since he developed a fascination for strongly correlated electron systems, quantum, and multifunctional materials that he investigates mainly using x-ray and neutron-based techniques.

3

报告人：Shigeyuki Komura，国科温州研究院

时间：6月3日（周二）16:00

单位：中国科学院理论物理研究所

地点：北楼202

4

报告人：Wang YAO，University of Hong Kong

时间：6月4日（周三）15:00

单位：北京大学物理学院

地点：西563会议室

摘要：

In this talk, I will discuss fractional quantum anomalous Hall effects in two occasions that are rather unconventional, hosted by lattice models that are variants of the three - orbital tight - binding model for twisted MoTe₂. The first is a singular flat band, with a protected touching point with a dispersive one. Such flat band can have some characters of a nearly ideal flat Chern band, except for the absence of a gap, which raises the question of whether fractional QAH states can be compatible with this band touching. I will show numerical evidences of FQAH states from both exact diagonalization and DMRG calculations. An interesting observation is the fractional QAH states exist in the limit of weak interaction strength, where the singular band touching feature is retained, but get quenched when larger interaction gaps the touching point and turn the singular flat band into a flat Chern band. The second occasion is in the opposite limit: an isolated flat band of zero Chern number, gapped from the rest bands that also have zero Chern number. And we will focus on the isolated band limit, namely interaction is always weaker than the gap, so that renormalisation by interaction leaves the flat quantum geometry and trivial topology unchanged. Starting with the Hartree - Fock band of zero Chern number, our ED calculations show unambiguous evidences of fractional QAH effect at its 2/3 filling. The ground state degeneracy rules out the relevance of band folding fractional crystal, and we do not expect there can be folded miniband to effectively display nontrivial band topology either. This example suggests that single particle topology is not the prerequisite for fractional quantum Hall state.

报告人简介：

Wang YAO obtained his BSc from Peking University in 2001, and PhD in physics from University of California, San Diego in 2006. He joined the University of Hong Kong in 2008, and rose through the academic ranks to Chair Professor of Physics in 2019. His group works in an interdisciplinary area across condensed matter physics, quantum physics, and optical physics, with current research interest in 2D quantum materials and their twisted structures. He is a New Cornerstone Investigator, and Fellow of American Physical Society and Fellow of Optica.

5

报告人：张俊杰，山东大学晶体材料全国重点实验室

时间：6月5日（周四）10:00

单位：清华大学物理系

地点： 物理楼W105

摘要：

高温超导机理和新型高温超导材料的探索一直是凝聚态物理领域的前沿研究课题。2023年中山大学王猛教授和清华大学张广铭教授领导的研究团队在双层镍氧化合物La3Ni2O7单晶中发现了临界转变温度78K@18.9 GPa的高温超导电性，引发了镍基高温超导研究热潮。经过1年多的研究，仍然存在一些关键基础科学问题亟待解决，包括超导转变温度能否提高，是否能在常压下实现镍基体块高温超导等。本报告中，我将介绍我们团队在镍基氧化物单晶生长、结构和物性研究方面取得的一些进展，主要包括：（1）开发镍基高温超导体单晶生长新方法，首次在常压下采用助熔剂法生长了La4Ni3O10-δ和La3Ni2O7-δ单晶，克服了高压制备条件，极大地降低了镍基超导研究单晶制备门槛，并在高压下观测到超导电性；（2）设计和发现了一类全新的、长程有序排列的杂化Ruddlesden-Popper层状镍氧化合物，在常压下生长了单层和双层杂化的RP相单晶，为探索新的镍基超导体提供了新的材料体系；（3）在常压下生长了高质量的双层镍氧化合物La2SmNi2O7单晶，其超导转变温度为92 K，零电阻温度73 K。发现高压下的最高超导转变温度与常压下的面内畸变正相关，指明了继续提升镍基超导Tc的方向。

报告人简介：

张俊杰，山东大学教授、博士生导师。2008年本科毕业于山东大学材料科学与工程学院，并保研晶体材料研究所，师从陶绪堂教授，硕博连读，于2013年获山东大学材料学博士学位。2013-2017年和2017-2019年先后在美国阿岗国家实验室John F. Mitchell课题组和橡树岭国家实验室Raphael P. Hermann课题组从事博士后研究。2019年11月入职山东大学。长期从事关联量子材料单晶生长、结构与物性研究工作，在Nat. Phys., Phys. Rev. Lett., PNAS, JACS等期刊上发表学术论文60余篇，引用2500余次，h因子26（Google Scholar）。2013年作为中国优秀博士研究生代表参加第63届林岛诺贝尔奖获得者大会，与34位诺贝尔奖得主面对面交流；2014年获山东省优秀博士学位论文；2016年获教育部自然科学二等奖（第四完成人）；2017年获美国物理学会DMP Post Doctoral Travel Awards。

6

报告人：Jaume Garriga，University of Barcelona

时间：6月5日（周四）10:30

单位：中国科学院理论物理研究所

地点：北楼322

摘要：
We discuss several inflationary mechanisms for seeding the formation of primordial black holes (PBH), which lead to a diversity of initial mass functions. Some scenarios are based on inflationary relics, such as high energy vacuum bubble remnants, while others are based on the collapse of standard adiabatic perturbations. We point out that the two mechanisms may often coexist. We also report on recent progress in determining the PBH mass function in a universe filled with nearly Gaussian adiabatic perturbations with an extended power spectrum. Our results may significantly impact overproduction bounds on the amplitude of the power spectrum, and tighten the viable mass range for primordial black holes as dark matter.

报告人简介：

Jaume Garriga is a Professor of Theoretical Physics at the University of Barcelona since 2021, following his tenure as associate professor at UAB/IFAE since 1994. He is a specialist in general relativity, quantum field theory in curved space, and inflation, with pioneering contributions to the theory of cosmological perturbations, brane world gravity and cosmology, and vacuum transitions in the multiverse. He received the Young investigator Distinction from the Generalitat de Catalunya in 2002. He is a founding member of the Gravitation, Strings and Cosmology consolidated group at the Institute of Cosmos Sciences of the University of Barcelona, ICCUB.

7

报告人：朱华星，北京大学

时间：6月5日（周四）15:00

单位：中国科学院理论物理所

地点：北楼CCAST五楼报告厅

8

报告人：殷嘉鑫，南方科技大学

时间：6月5日（周四）15:00

单位：北京大学物理学院

地点：物理大楼中212报告厅

摘要：

本次报告将介绍笼目晶体材料的研究进展，着重讨论我们观测到的陈数拓扑磁体、手性电荷序和磁性超导电性等一系列兼具拓扑与关联的量子物态。这些观测开启了拓扑笼目磁体与超导体的探索之路，揭示了阻挫材料中电磁耦合与量子调控的基本规律，为下一代量子器件发展提供了新思路。

报告人简介：

殷嘉鑫本科毕业于中国科学技术大学，在物理研究所取得博士学位，后在美国普林斯顿大学任博士后与研究员。2022年他加入南方科技大学物理系，任副教授。他研究方向为利用先进能谱手段发现、理解和调控固体材料中的电子结构。他已发表多篇论文，含11篇Nature/Science, 14篇Nature Physics/Nature Materials/Nature Reviews，36篇PRL/NC等。

9

报告人：Jianghui Ji，中国科学院紫金山天文台

时间：6月5日（周四）15:30

单位：北京大学物理学院

地点：KIAA-auditorium

摘要：

The detection and study of potentially habitable exoplanets is a cutting-edge topic in contemporary astronomy. The National Medium- and Long-Term Development Plan for Space Science (2024–2050) has been officially released, identifying “Nearby Habitable Exoplanets” as one of its key scientific frontiers.The Closeby Habitable Exoplanet Survey (CHES) (http://www.ps.pmo.cas.cn/CHES/)) aims to search for Earth-like planets in the habitable zones around 100 nearby Sun-like stars located within approximately 32 light-years of the Solar System. Utilizing micro-arcsecond-level space-based astrometry, CHES will conduct a comprehensive census of nearby planetary systems, determining the true masses and three-dimensional orbital parameters of detected planets, and establishing a complete database of nearby exoplanets.

The CHES telescope features a 1.2-meter aperture and will operate at the Sun-Earth Lagrangepoint L2 for a planned five-year scientific mission. The mission is expected to achieve significant breakthroughs in detecting terrestrial planets within the habitable zones of nearby solar-type stars. With its innovative technological approach, CHES offers unique advantages in the search for potentially habitable Earth-like planets.This pioneering research will address fundamental questions such as:What is the distribution of nearby habitable exoplanets?Is Earth unique?andHow do planets become cradles of life?

报告人简介：

Dr. Jianghui JI is a Research Professor and Director of the Laboratory at Purple Mountain Observatory, Chinese Academy of Sciences (CAS). He serves as Chair of the Planetary Science Division of the Chinese Astronomical Society and Director of the CAS Key Laboratory of Planetary Sciences. He is also a recipient of the National High-level Talent Program. His research focuses on exoplanets, protoplanetary disks, and small bodies in the Solar System. He has authored over 200 scientific publications. He has led several major research projects, including a Key Program of the National Natural Science Foundation of China and the CAS Strategic Priority Program on Space Science. His work has been recognized as part of China's Top Ten Astronomical Advances of the Year on three occasions and has earned him the Jiangsu Provincial Science and Technology Award. He has also been frequently invited to deliver plenary and keynote talks at international conferences.

10

报告人：徐英轩，柏林洪堡大学

时间：6月9日（下周一）14:00

单位：中国科学院理论物理所

地点：北楼202

摘要：

The computation of scattering amplitudes connects formal theory, phenomenology, and experiment. Feynman integrals, as the most established method for evaluating scattering amplitudes, encounter growing computational challenges as experimental precision increases. Integration-by-parts (IBP) reduction, though widely used, often becomes the main bottleneck in the evaluation process. Our package, NeatIBP1.1 + Kira, uses syzygy and module intersection techniques to generate compact IBP systems and performs automatic reduction using Kira, significantly improving reduction efficiency. The latest version also incorporates the spanning cuts method, further reducing the overall computational complexity for particularly demanding problems.

报告人简介：

Dr. Yingxuan Xu is currently a postdoctoral researcher at Humboldt University of Berlin, where he also earned his PhD in Physics in 2025. His research focuses on the computation of scattering amplitudes in high-energy and gravitational physics, including QCD Feynman integrals, amplitude calculations in gravitational wave processes, and the development of novel computational techniques.

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