报告人：彭练矛，北京大学教授
时间：5月31日（周四）16:00
单位：清华大学
地点：理科楼郑裕彤讲堂
随着硅基微电子器件尺度进入深亚微米后，后摩尔时代非硅电子学的发展备受瞩目。国际半导体技术路线图(ITRS)委员会2005年明确指出硅基CMOS技术将在2020年左右达到其性能的绝对极限。在可能的下一代技术中，ITRS委员会基于其新材料和新器件工作组的系统研究和推荐，2009年明确向半导体行业推荐碳基电子学，作为可能在未来10-15年显现商业价值的下一代电子技术，并给出了详尽的路线图和碳纳米管材料挑战。面向后摩尔时代，北京大学于1999年组建了碳基纳电子材料与器件研究团队。经过近二十年的努力，该团队在碳基电子器件相关材料和制备工艺的研究中取得系列突破，基本解决了ITRS给出的碳管材料挑战，发展了一整套碳管CMOS集成电路和光电器件的制备新技术，成为下一代信息处理技术强有力的竞争者；其核心为放弃掺杂，通过控制电极材料达到选择性地向晶体管注入电子或空穴，实现晶体管极性的控制，并首次制备出高性能对称碳管CMOS电路。2017年，首次基于碳管实现了栅长为5纳米的CMOS器件，证明器件在本征性能和功耗综合指标上相对硅基器件具有10倍以上的综合优势，并接近由量子测不准原理决定的电子器件理论极限。该团队的上述工作，2015年被Nature Index China选做北京的代表性创新工作之一，称其“代表着计算机处理器的未来”；2017年又被选为封面文章《中国的蓝芯未来》重点报道。《人民日报》（海外版）在《中国芯走出自强路》专文中评价该团队碳管晶体管的工作“是中国信息科技发展的一座新里程碑”。
报告人：Linfeng Zhang，Princeton University
时间：5月29日（周二）10:00
单位：中科院物理所
地点：M楼830
Machine learning models are changing the paradigm of molecular modeling. Of particular interest is the inter-atomic potential energy surface (PES). In this talk, I would introduce deep learning-based PES models that we recently developed [1-3]. I would focus on how to construct a PES model that is end-to-end, accurate, and scalable, and preserves all the natural symmetries. Further, I would show the performance of these models when describing finite and extended systems including organic molecules, metals, semiconductors, and insulators. The corresponding open-source software [4] is efficiently parallelized and interfaced with popular machine learning and molecular dynamics packages.
报告人：Xiaoze Liu, University of California, Berkeley
时间：5月30日（周三）10:30
单位：清华大学
地点：理科楼C302报告厅
Light and matter are distinct physical entities that can strongly interact with each other. In the scheme of cavity quantum electrodynamics (CQED), light and matter can be “married” to demonstrate unprecedented phenomena by taking advantages of both constituents. The solid state platform provides a convenient and efficient testbed to explore the underlying physics and optoelectronic applications in CQED. In this seminar, I will first introduce new hybrid quasiparticles by the “marriage” of light (i. e., photon) and matter (i. e., exciton) in the strong coupling regime of solid state CQED. The hybrid quasiparticles called exciton-polaritons take advantages of excitons and photons, leading to interesting physics and applications such as high-temperature Bose-Einstein condensation, superfluidity, photon blockade and inversionless lasers. Specifically, I will discuss the formation and coherent control of exciton-polaritons in an optical cavity embedded with two-dimensional (2D) semiconductors. As one typical example of the emerging materials, 2D semiconductors show unique excitonic properties due to large quantum confinement. These properties overcome limitations of conventional quantum well systems, and are inherited to the 2D exciton polaritons for table-top demonstration of profound quantum phenomena. Following this, I will also present some of our recent progress on the perovskite semiconductors with Rydberg excitons in CQED. The Rydberg exciton series in perovskites demonstrate large oscillator strengths and thus can be strongly coupled to cavity photons. The observation of Rydberg exciton polaritons and its condensation indicates great applications for quantum optics and energy-efficient devices. Finally, I will briefly talk about some future ideas (long-term and short terms) on the quantum study of these excitonic materials in CQED and efficient optoelectronic applications.
4CHIRAL SPINTRONICS
报告人：See-Hun Yang
时间：5月30日（周三）16:00
单位：北京大学
地点：Room W563, Physics Building
Chirality is one of the fundamental asymmetries in nature. Recently chiral nature of specific magnetic structures has been enormous attention and arisen to be very useful for potential application to spintronics since it has been realized that the combination with spin-orbit interaction such as spin Hall effect can be very efficient in manipulation of magnetic elements [1]. In this talk I will present a variety of novel emergent phenomena associated with chiral properties from emergent magnetic nanostructures: spin-orbit torques from perpendicularly magnetized ultrathin films [2], exchange coupling torque [3] and chiral exchange drag [4] from synthetic antiferromagnets, and chiral tunneling from chiral molecules [5]. In the end I will conclude my talk with promising outlooks from these new findings.
报告人：秦庆，中科院高能所
时间：5月30日（周三）18:30
单位：中国科学院大学
地点：雁栖湖校区教1-113
报告人：Yongmin Cho，Konkuk University
时间：5月31日（周四）10:00
单位：中科院理论所
地点：Conference Room 6420, ITP new building
We discuss the cosmological implications of electroweak monopole of the standard model. Although the electroweak phase transition is of the first order, the cosmological monopole production comes from the thermal fluctuations of the Higgs field after the phase transition, not the vacuum bubble collisions during the phase transition. But most of the monopoles produced initially are annihilated quickly. As the result the remnant monopole density at present universe becomes very small, of $10^{-11}$ of the critical density. Nevertheless the monopole could become the seed of the primodial blackholes and the large scale structure of the universe, and trigger the electroweak baryon genesis. Moreover it could be the source of the intergalactic magnetic field. We discuss how to detect the remnant monopole experimentally.
报告人：Yingying Peng，Department of Physics, University of Illinois at Urbana-Champaign
时间：5月31日（周四）14:00
单位：中科院物理所
地点：物理所M236会议室
The origin of unconventional superconductivity (SC) remains one of the most important challenges in condensed matter physics. Despite the diversity of materials, unconventional SC emerges nearly always in proximity to another ordered state, such as spin order and charge order, suggesting a fundamental connection between SC and charge/spin fluctuations. In this talk, I will describe the resonant inelastic X-ray scattering (RIXS) technique which has huge potential to probe several kinds of excitations at a time, from charge excitations to orbital excitations, to spin waves and lattice modes. I will show our recent RIXS studies probing magnetic excitations and charge orders in cuprates. These include: (i) The relationship between the crystal structure and the extent of hopping integrals in parent compounds, and the detrimental role of apical oxygens in superconductivity. (ii) The evolution of the magnetic excitations across the entire phase diagram of cuprates. (iii) Discovery of a re-entrant charge order outside the pseudogap regime in overdoped (Bi,Pb)2.12Sr1.88CuO6+δ, showing the ubiquitous of charge order across the entire phase diagram and inviting revision of theories that posit an essential link between the charge order and pseudogap states.
报告人：Wei-Min Gu，Xiamen Univ.
地点：蒙民伟科技南楼S727
In my talk, I will first review the progress on black-hole accretion disk models in the past 45 years. By taking the thermal equilibrium into consideration, I will discuss the physical reason for outflows in accretion systems. In addition, I will briefly introduce our recent works on the applications of accretion models to ultraluminous X-ray sources and gamma-ray bursts.
报告人：Qing-hong CAO，Physics School, Peking University
地点：KIAA-PKU Auditorium
Thousands of physicists are working diligently to search for new physics beyond the Standard Model of particle physics on the Large Hadron Collider. Many searches are related to the top quark and Higgs boson physics. In this talk I will review the history of top quark and Higgs boson discoveryand present a few new physics models which are dear to my heart.
报告人：Jiadong Zang，Department of Physics, University of New Hampshire
时间：6月1日（周五）10:30
单位：中国科学院物理所
地点：M楼253
Chiral magnets are a series of magnets with broken inversion symmetry. A new type of spin interaction therein, the Dzyaloshinskii-Moriya interaction, stimulates the formation of many novel topological spin textures. One typical example is the emergence of magnetic skyrmion, whose nontrivial topology enables unique dynamical property and thermal stability and gives out promise on future magnetic memory devise. Inspired by skyrmions, in this talk, I will give a comprehensive introduction of skyrmions and their behavior in confined geometries. I will also present three other relevant spin textures in chiral magnets. One is the target skyrmion we recently observed, both theoretically and experimentally, in ultra-small nanodisks of chiral magnets. Zero-field target skyrmions and their polarization switch will be discussed. Putting in heterostructures, we also found a new type of topological configuration dubbed the Hopfion therein. Finally, I will discuss emergent topology driven by thermal fluctuations.
报告人：Duncan Lorimer，West Virginia University
时间：6月1日（周五）12:00
单位：北京大学
地点：meeting room of first floor, KIAA
报告人：Yongmin Cho，韩国建国大学
时间：6月1日（周五）15:30
单位：北京师范大学
地点：物理楼106
We discuss the cosmological implications of electroweak monopole of the standard model. Although the electroweak phase transition is of the first order, the cosmological monopole production comes from the thermal fluctuations of the Higgs field after the phase transition, not the vacuum bubble collisions during the phase transition. But most of the monopoles produced initially are annihilated quickly. As the result the remnant monopole density at present universe becomes very small, of $10^{-11}$ of the critical density. Nevertheless the monopole could become the seed of the primodial blackholes and the large scale structure of the universe, and trigger the electroweak baryon genesis. Moreover it could be the source of the intergalactic magnetic field. We discuss how to detect the remnant monopole experimentally.
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