非常規高溫超導、里德伯原子量子模擬、太赫茲發射光譜、量子霍爾效應 | 本周物理講座

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

時間：4月7日（周二）10:00

單位：清華大學物理系

地點：物理樓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.

報告人簡介:

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.

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

時間：4月7日（周二）14:00

單位：中國科學院物理研究所

地點：D樓206會議室

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.

報告人簡介:

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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報告人：Lode Pollet, Ludwig Maximilian University of Munich

時間：4月8日（周三）10:00

單位：中國科學院物理研究所

地點：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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報告人：聞海虎，南京大學物理學院

時間：4月9日（周四）10:00

單位：中國科學院物理研究所

地點：M236會議室

摘要:

Bardeen-Cooper-Schrieffer在1957年創立了著名的BCS理論，第一次讓人類認識到超導發生的根本原因是電子系統配對以后發生凝聚，形成一個宏觀量子相干態。該理論認為電子配對是通過交換虛聲子而發生的，因此在該理論框架下高溫超導就需要好的庫倫屏蔽、高德拜溫度和強的電聲子耦合。然而銅基、鐵基和鎳基高溫超導體卻表現出來全新的要素和規律。本報告試圖從它們表現出來的共性出發談一談對高溫超導的理解。首先要有強的反鐵磁類的超交換能，正是這種超交換提供了電子配對的原始驅動力；其次要有很好匹配的電子巡游自由度，建立起超流密度和相位相干。這兩者在銅基、鐵基和鎳基系統中因為電子結構的不同，會有所差異，但是都有一定的證據，并且好的超導態需要這兩者得到很好的統一。我們將從這些材料的基本特性出發，探討它們所表現出來的共性結果，如能隙結構和可能的BEC-BCS轉變等。

報告人簡介:

聞海虎教授是南京大學物理學教授，美國物理學會會士（2013）。長期從事超導材料和物理問題研究，在高溫超導體磁通動力學、高溫超導機理問題和非常規超導材料合成方面獲得一系列科研成果，先后三次獲得國家自然科學獎，二等獎兩次(2004，2023，均第一完成人)，一等獎一次(2013，第四完成人)。此外還獲得中國青年科技獎（2000），海外華人物理學會亞洲成就獎（2010），香港求是基金杰出科技成就集體獎（2009），德國洪堡研究獎（2025）等獎項。在Nature，Nature子刊和Science子刊等SCI 雜志上發表論文 510 余篇，文章被他人引用超過14000余次，h-index 67, 在國內外重要學術會議上作邀請報告過百場。目前還兼任亞太物理學會-凝聚態物理分會主席， Science China-PMA, Philosophical Magazine 等雜志編委等。

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報告人：陶鎮生，復旦大學

時間：4月9日（周四）10:00

單位：中國科學院物理研究所

地點：M253會議室

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.

報告人簡介:

陶鎮生，復旦大學物理學系研究員、博士生導師。本科和碩士畢業于復旦大學物理學系，博士畢業于美國密歇根州立大學物理天文系。多年來圍繞超快光學、超快光物質相互作用方向開展了多項原創工作。至今在包括Science, Nature Nanotechnology, eLight, Light:Science&Applications，PRL等刊物發表論文50余篇。先后獲得國家 “高層次海外青年人才”，德國“洪堡學者”，上海市“東方學者”特聘教授。

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報告人：梁田，清華大學

時間：4月9日（周四）14:00

單位：中國科學院物理研究所

地點：M249會議室

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.

報告人簡介:

梁田，清華大學物理系副教授。2009年、2011年分別本科、碩士畢業于日本東京大學物理系，2016年于美國普林斯頓大學物理系獲博士學位。2016年至2018年、2018年至2021年分別擔任美國斯坦福大學博士后、日本理化學研究所特別研究員。2021年加入清華大學物理系，主要研究方向為拓撲量子材料的輸運與光學測量。至今已發表近40篇論文，其中包括Nature及子刊8篇、 Science及子刊2篇、PNAS與PRL 7篇、以及其他論文20余篇。總引用數8000余次。現任科技部重點研發計劃（青年項目）首席科學家。

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報告人：Frank Pollmann, Technical University of Munich

時間：4月9日（周四）15:00

單位：中國科學院物理研究所

地點：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.

報告人簡介:

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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