非常规高温超导、里德伯原子量子模拟、太赫兹发射光谱、量子霍尔效应 | 本周物理讲座

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报告人：Prof. Vadim Grinenko, Tsung-Dao Lee Institute & School of Physics and Astronomy, Shanghai Jiao Tong University

时间：4月7日（周二）10:00

单位：清华大学物理系

地点：物理楼W105

摘要:

The nature of the broken time reversal symmetry (BTRS) state in Sr2RuO4 remains a long-standing puzzle, and its relation to superconductivity remains controversial. There are various universal predictions for the BTRS state when it is associated with a multicomponent superconducting order parameter. In particular, in the BTRS superconducting state, spontaneous fields appear around crystalline defects, impurities, superconducting domain walls and sample surfaces. Here, we aimed to verify these predictions for Sr2RuO4 by performing muon spin relaxation (μSR) measurements on Sr2−xLaxRuO4 single crystals. We observed that the enhanced muon spin depolarisation rate in the superconducting state ∆Λ, monotonically decreases with La doping. The observed behaviour is consistent with ∆Λ ∝ Tc2, indicating that homogeneous La substitution is not a source of spontaneous magnetic fields, but the spontaneous fields are altered by the suppression of superconducting critical temperature (Tc) with La-doping. Qualitatively different behaviour is observed for the effects of disorder and Ru inclusions. By analysing a large number of samples measured in the previous works, we found that the ∆Λ is small for pure Sr2RuO4 single crystals and increases with disorder or impurities. The strongest enhancement is observed in the crystals with Ru-inclusions, which show enhanced Tc. The comparative study allowed us to conclude that spontaneous fields in the BTRS superconducting state of Sr2RuO4 appear around inhomogeneities and, at the same time, decrease with the suppression of Tc. The observed behaviour is consistent with the prediction for multicomponent BTRS superconductivity.

报告人简介:

Vadim Grinenko graduated from the National Research Nuclear University (MEPhI), Moscow, in 2004. He got a PhD in the National Research Center "Kurchatov Institute", Moscow, in 2008. After his PhD, he moved to Germany and joined the Institute for Metallic Materials in IFW Dresden, Germany, as a postdoc. At the end of 2015, Vadim moved to TU Dresden, Germany, as a PI. In 2015 and 2016, he was a visiting Associate Professor at Nagoya University. In 2022, Vadim moved to the TD Lee Institute in Shanghai. Now, he is a Tenured Fellow at TD Lee Institute and a Tenured Associate Professor at Shanghai Jiao Tong University. He works in the field of superconductivity and magnetism and has more than 70 publications.

2

报告人：Mark D. Ediger，University of Wisconsin-Madison

时间：4月7日（周二）14:00

单位：中国科学院物理研究所

地点：D楼206会议室

摘要:

In the last 15 years, we have learned that physical vapor deposition (PVD) can prepare ultrastable and anisotropic glasses with striking material properties.  Almost all of this work has been performed on single component systems.  The investigation of multicomponent PVD glasses is motivated by the technological importance of co-deposited glasses of organic semiconductors for the production of organic light emitting diode (OLED) displays.  For co-deposited systems, we are interested in understanding how to form stable glasses, predict anisotropic packing, and control component dispersion.  In the last three years, we have investigated co-deposition of roughly a dozen pairs of molecules, utilizing components that form ultrastable glasses as pure materials.

Most of our codepositions yield ultrastable glasses (high density, high kinetic stability, low enthalpy), which generally have about the same stability as vapor-deposited glasses of the pure components.  Surprisingly, this occurs even when the two components have strikingly different Tg values (Tg,A/Tg,B = 1.5); we interpret this to mean that both components are highly mobile at the free surface for depositions near 0.85 Tg,mixture.  DSC measurements are a useful tool for these systems.  For these mixed ultrastable systems, average molecular orientation can be predicted from single component data.

In a few cases, co-deposition results in glasses in which the components are partially segregated.  For example, when DO37 is codeposited with TPD, domains from 30 – 120 nm are formed, depending upon the substrate temperature. DO37 and TPD are not miscible in the liquid state, which explains the thermodynamic driving force for domain formation.  Soft x-ray scattering is a useful tool for characterizing domain formation.

报告人简介:

Professor Mark D. Ediger is the Hyuk Yu Professor of Chemistry at the University of Wisconsin–Madison and an Associate Editor of The Journal of Chemical Physics. He received his Ph.D. from Stanford University in 1984 and joined UW–Madison that same year as an assistant professor, where he has remained ever since. He is internationally recognized for his influential work on glassy materials, especially supercooled liquids, polymer glasses, and ultrastable glasses formed by physical vapor deposition. His honors include the American Physical Society’s John H. Dillon Medal in 1993, the National Science Foundation’s Special Creativity Award in 2006, the American Chemical Society’s Joel Henry Hildebrand Award in 2013, and the American Physical Society’s Polymer Physics Prize in 2015.

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报告人：Lode Pollet, Ludwig Maximilian University of Munich

时间：4月8日（周三）10:00

单位：中国科学院物理研究所

地点：M830

摘要:

Rydberg tweezer arrays provide a versatile platform to explore new types of strongly correlated many-body physics. Different types of interactions, such as dipolar XY,  van-der-Waals Ising  ZZ, and spin-flip terms, can simultaneously exist. Furthermore, the Rydberg blockade mechanism can be used to prevent the excitation of another, nearby-situated Rydberg atom akin to the Gauss law in lattice gauge theory. In the talk I give an overview of the current state of the art and discuss pros and cons of this approach bridging the fields of quantum magnetism, super-solids, transfer loading from tweezers to optical lattices, spin squeezing, dynamically prepared topological states, and comment on hybrid analog-digital approaches.

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报告人：闻海虎，南京大学物理学院

时间：4月9日（周四）10:00

单位：中国科学院物理研究所

地点：M236会议室

摘要:

Bardeen-Cooper-Schrieffer在1957年创立了著名的BCS理论，第一次让人类认识到超导发生的根本原因是电子系统配对以后发生凝聚，形成一个宏观量子相干态。该理论认为电子配对是通过交换虚声子而发生的，因此在该理论框架下高温超导就需要好的库伦屏蔽、高德拜温度和强的电声子耦合。然而铜基、铁基和镍基高温超导体却表现出来全新的要素和规律。本报告试图从它们表现出来的共性出发谈一谈对高温超导的理解。首先要有强的反铁磁类的超交换能，正是这种超交换提供了电子配对的原始驱动力；其次要有很好匹配的电子巡游自由度，建立起超流密度和相位相干。这两者在铜基、铁基和镍基系统中因为电子结构的不同，会有所差异，但是都有一定的证据，并且好的超导态需要这两者得到很好的统一。我们将从这些材料的基本特性出发，探讨它们所表现出来的共性结果，如能隙结构和可能的BEC-BCS转变等。

报告人简介:

闻海虎教授是南京大学物理学教授，美国物理学会会士（2013）。长期从事超导材料和物理问题研究，在高温超导体磁通动力学、高温超导机理问题和非常规超导材料合成方面获得一系列科研成果，先后三次获得国家自然科学奖，二等奖两次(2004，2023，均第一完成人)，一等奖一次(2013，第四完成人)。此外还获得中国青年科技奖（2000），海外华人物理学会亚洲成就奖（2010），香港求是基金杰出科技成就集体奖（2009），德国洪堡研究奖（2025）等奖项。在Nature，Nature子刊和Science子刊等SCI 杂志上发表论文 510 余篇，文章被他人引用超过14000余次，h-index 67, 在国内外重要学术会议上作邀请报告过百场。目前还兼任亚太物理学会-凝聚态物理分会主席， Science China-PMA, Philosophical Magazine 等杂志编委等。

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报告人：陶镇生，复旦大学

时间：4月9日（周四）10:00

单位：中国科学院物理研究所

地点：M253会议室

摘要:

The orbital angular momentum of electrons offers a promising, yet underexplored, degree of freedom for ultrafast, energy-efficient information processing. As the foundation of orbitronics, understanding how orbital polarizations propagate and convert into charge currents is essential but remains elusive due to the challenge in disentangling orbital and spin dynamics in thin films. While some theoretical studies predict that orbital transport is constrained to sub-atomic-layer scales in materials, recent experiments have reported exceptionally long orbital diffusion lengths. To address this contradiction, we combine terahertz emission spectroscopy with a wedge-sample platform to systematically investigate spin and orbital transport in heavy metals with sub-nanometer resolution. Our measurements access the previously unexplored thin-film regimes (<3 nm), uncovering anomalous behaviors that challenge the prevailing interpretations of long-range orbital transport. We consistently find the orbital diffusion lengths (λL) to be substantially shorter than the spin diffusion lengths (λS) in heavy metals, with λL in W approaching 0.36 nm. Interface-sensitive control experiments further rule out interfacial orbital-to-charge conversion as the dominant mechanism, supporting the bulk inverse orbital Hall effect as the primary conversion process.

报告人简介:

陶镇生，复旦大学物理学系研究员、博士生导师。本科和硕士毕业于复旦大学物理学系，博士毕业于美国密歇根州立大学物理天文系。多年来围绕超快光学、超快光物质相互作用方向开展了多项原创工作。至今在包括Science, Nature Nanotechnology, eLight, Light:Science&Applications，PRL等刊物发表论文50余篇。先后获得国家 “高层次海外青年人才”，德国“洪堡学者”，上海市“东方学者”特聘教授。

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报告人：梁田，清华大学

时间：4月9日（周四）14:00

单位：中国科学院物理研究所

地点：M249会议室

摘要:

The four-dimensional quantum Hall effect (4D QHE) was first theoretically proposed by S.C. Zhang et al. in 2001 and is closely related to the SU(2) Yang monopole in five-dimensional space. For a long time, this theory lacked suitable material systems for experimental verification. In 2008 and 2009, the groups of S.C. Zhang and D. Vanderbilt independently demonstrated that, by treating three-dimensional space together with time as a four-dimensional parameter space, the 4D QHE can manifest as the topological magnetoelectric effect (TME) in three-dimensional topological insulators. Analogous to the two-dimensional quantum Hall effect characterized by the first Chern number, the 4D QHE is characterized by the second Chern number. Currently, three-dimensional topological insulators serve as the primary material platform for 4D QHE research, but the expected TME signal is extremely weak, necessitating ultra-high-sensitivity measurement techniques.

In this talk, I will present our recent breakthroughs in addressing this long-standing experimental challenge. First, using the quantum anomalous Hall (QAH) system as a validation platform, we developed an ultra-sensitive out-of-plane charge accumulation measurement technique with a resolution of <0.1 fC/Gs, achieving the first observation of quantized charge accumulation in the multi-domain 4D QHE regime. Second, we pioneered an active capacitive compensation method that introduces an effective negative capacitance in the gate line, equivalently enhancing the gate capacitance. This approach successfully recovered over 95% of the severely attenuated signal in QAH samples, removing a key technological barrier for single-domain 4D QHE detection.

With these core technologies established, we are now positioned to pursue the final experimental observation of the 4D QHE through both transport and optical measurement approaches. This talk will provide a comprehensive overview of the scientific concepts, technical innovations, and future directions of our research, highlighting our systematic progress toward unveiling this fundamental topological phenomenon. If time permits, other directions of ongoing research in my lab will also be presented.

报告人简介:

梁田，清华大学物理系副教授。2009年、2011年分别本科、硕士毕业于日本东京大学物理系，2016年于美国普林斯顿大学物理系获博士学位。2016年至2018年、2018年至2021年分别担任美国斯坦福大学博士后、日本理化学研究所特别研究员。2021年加入清华大学物理系，主要研究方向为拓扑量子材料的输运与光学测量。至今已发表近40篇论文，其中包括Nature及子刊8篇、 Science及子刊2篇、PNAS与PRL 7篇、以及其他论文20余篇。总引用数8000余次。现任科技部重点研发计划（青年项目）首席科学家。

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报告人：Frank Pollmann, Technical University of Munich

时间：4月9日（周四）15:00

单位：中国科学院物理研究所

地点：M236

摘要:

Quantum fluctuations and interactions give rise to exotic phases of matter with remarkable properties, pushing the boundaries of our understanding of many-body quantum systems. Solving these problems is notoriously difficult on classical computers due to the exponential complexity of quantum many-body physics. Quantum processors, however, open new avenues for exploring these systems, offering a direct and potentially transformative approach. In this talk, we will first discuss recent progress in realizing and visualizing dynamics of charges and strings in (2+1)D lattice gauge theories. We will then investigate a class of novel, highly entangled quantum phases that exist only in non-equilibrium settings and demonstrate how to probe their stability using a quantum processor.

报告人简介:

Frank Pollmann is a Professor at the Technical University of Munich (TUM). He earned his Ph.D. from the Max Planck Institute for the Physics of Complex Systems in Dresden and conducted postdoctoral research at the University of California, Berkeley. His research focuses on theoretical condensed matter physics, with a particular emphasis on strongly correlated electron systems. Prof. Pollmann has been recognized with numerous prestigious awards, including the Walter Schottky Prize from the German Physical Society (DPG) and an ERC Consolidator Grant. His recent work significantly contributes to the field of quantum simulation, leveraging near-term quantum hardware to explore complex many-body phenomena and lattice gauge theories.

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