团簇研究走向原子制造 | 本周物理学讲座

来源：中国物理学会期刊网

1团簇研究走向原子制造

报告人：宋凤麒，南京大学

时间：12月19日（周四）10:00

单位：中科院物理研究所

地点：M楼236会议室

原子团簇是由若干乃至上万个原子组成的结构相对稳定的微观聚集体，具有随着原子数激烈变化的结构和物性，是原子分子物理和凝聚态物理的桥梁。近年来团簇科学逐渐从谱学研究走向原子级材料与器件的研究，本报告将介绍南京大学原子制造课题组在这方面的努力：1）建立质量选择团簇束流源；2）研究团簇修饰拓扑/石墨烯体系的电子输运；3）研究单团簇器件的电子输运；4）研究团簇随着原子数变化的等离激元。本报告还将介绍团簇走向原子制造方面的发展考虑。

2波粒二象性之新检验：理论分析和实验验证

报告人：李志远，华南理工大学

时间：12月17日（周二）15:00

单位：中科院物理研究所

地点：M楼830会议室

微观粒子具有波粒二象性，它们有时表现为粒子性（有确定的路径，但不产生干涉条纹），有时表现为波动性（没有确定的路径，但产生干涉条纹），依赖于观察者如何去观测它们的运动行为，但是两者不可能同时被观测到。波粒二象性是量子力学的概念基础，也一直是量子物理中迷雾重重的一个待解之问题。

本报告将介绍作者在利用光子和原子干涉仪检验微观粒子波粒二象性这一量子物理基础问题上的20年思考，以及近5年来所获得的理论和实验研究进展。作者将从量子力学的基本操作规则出发，对几种经典干涉仪以及作者首创的弱测量光子和原子干涉仪做系统的量子力学分析，求解出这些干涉仪中微观粒子波函数演化的行为，在此基础上计算出微观粒子干涉条纹的可见度V和运动路径的可辨别度D，从而对微观粒子波动性和粒子性的可观测性进行定量化的评估。理论计算结果表明，利用弱测量光子和原子干涉仪可以突破正统的波粒二象性原理对波动性和粒子性同时观测所施加的理论限制。在理论研究的指引下，作者和合作者开展了单光子实验，结果完全证实了理论的预言。弱测量光子和原子干涉仪的提出及其深入的理论和实验研究，打开了同时观测微观粒子的波动性和粒子性的一条通道，有望为量子力学建立更加牢固可靠的概念基础提供有益的思路。

3New insight into high-Tc cuprates offered by photon scattering

报告人：李源，北京大学量子材料科学中心

时间：12月18日（周三）10:00

单位：中科院物理研究所

地点：M楼236会议室

High-Tc cuprate superconductors are well-known for their antiferromagnetism inherited from the Mott-insulating parent compounds. Visible (Raman) and invisible (X-ray) photon scattering experiments, in particular those that utilize resonant enhancement, allow us to probe dynamic antiferromagnetic spin correlations with excellent sensitivity. In this talk, I will present results obtained by applying these combined methods to the first two members of the Hg-family of cuprates, Hg1201 and Hg1212. The central finding may be regarded as a magnon counterpart of the isotope effect in conventional superconductors: the single- and bi-magnon energies are found to undergo significant increases from Hg1201 to Hg1212 that correlate with the rises in the superconducting energy gap and Tc. Together with superconductivity’s feedback on the spin excitations, these results strongly support a magnetic pairing mechanism.

4Structural aspects of deformation defects in bulk metallic glasses

报告人：Yang Tong，Materials Science and Technology Division, Oak Ridge National Laboratory, USA

时间：12月18日（周三）14:30

单位：中科院物理研究所

地点：D楼211会议室

Metallic glasses have liquid-like structure without well-defined topological defects like dislocations in metals and alloys. My presentation will address three critical issues related to the mechanical behavior of metallic glasses: (a) Identification of deformation defects in metallic glasses. High energy X-ray diffraction experiment was conducted—using anisotropic pair distribution function—to characterize the size and stress relaxation ability of defects in metallic glasses activated by external stresses; (b) Identification of two local stress relaxation modes that control macroscopic mechanical properties in metallic glasses. Using the defect characterization method based on high energy X-ray diffraction, two different local stress relaxation modes was observed in defect regions, which are responsible for inhomogeneous and homogeneous deformation, respectively; (c) Structural rejuvenation method was developed to improve and recover the compressive plasticity. The microscopic mechanism of structural rejuvenation was unveiled by structural study and molecular dynamics simulation. Our findings are discussed in the context of pre-yield structural excitations, structural relaxation and rejuvenation, as-well as mesoscopic effects of shear banding during plastic flow.

5Quantum Simulation and Quantum Information Control with Ultracold Atoms

报告人：金政，James Franck institute, Enrico Fermi institute and Department of Physics, University of Chicago；Department of physics, Tsinghua University

时间：12月19日（周四）16:00

单位：清华大学

地点：理科楼郑裕彤讲堂

Laser cooling and trapping of atoms embarks an exploration into a new world where quantum mechanics dominates all laws of motion. New tools to precisely manipulate the atoms are developed, which remarkably advance quantum simulation and quantum metrology.  I will outline in this lecture the basics of quantum control with cold atoms, as well as examples of quantum simulation of nuclear, condensed matter and gravitational systems. Finally I will outline our new experiment to gain full control of a many-body Hamiltonian toward scalable quantum information processing.

6Searching for transformative materials beyond graphene: The rise of indium selenide

报告人：Amalia Patanè，School of Physics and Astronomy，University of Nottingham

时间：12月20日（周五）10:00

单位：清华大学

地点：物理系理科楼C302

The search for transformative materials beyond traditional covalent semiconductors, such as Si, has led to fast growing activities on new two-dimensional (2D) semiconductors and the exciting growing development of the metal chalcogenide indium selenide, InSe. This 2D crystal exhibits strong covalent atomic bonds in the layer plane and van der Waals (vdW) attraction between the layers, enabling the isolation of high-quality stable thin films down to the atomic monolayer thickness. The science and technology of 2D InSe represent a rapidly developing and vibrant field with breakthroughs emerging from both experiment and theory. This 2D semiconductor has a high photoresponsivity from the infrared (IR) to the ultra-violet (UV) spectral range; a low mass conduction band electrons and high electron mobility even in atomically thin films, larger than in Si-based field effect transistors (FETs); high mechanical strength; a strain-sensitive band structure; a density of states with 1D van Hove singularities, etc In this talk, I will present my recent research on 2D InSe and its heterostructures, and discuss emerging activities with prospects for digital ultra-thin electronics and nanophotonics.

7高能重离子碰撞过程的整体极化效应与自旋物理

报告人：梁作堂，山东大学

时间：12月20日（周五）14:00

单位：北京航天航空大学

地点：北校区沙河主楼C座511会议室

在高能重离子碰撞过程中参与反应的系统有巨大的轨道角动量,由于强相互作用中自旋轨体耦合，该巨大的轨道角动量将导致产生的夸克胶子等离子体的整体极化。

整体极化效应被我国理论工作者提出十几年后被美国布鲁克海文国家实验室相对论重离子撞机实验所证实,引发广泛关注,使重离子碰撞过程自旋物理成为高能核物理领域当前热门研究方向之一。本报告的目标是介绍整体极化的原始思想、近期的发展以及面临的机遇与挑战。

8Anomalous antiferromagnetism in metallic Ruo2 determined by resonant X-ray scattering

报告人：朱志海,中科院物理所

时间：12月20日（周五）10:00

单位：北京航天航空大学

地点：沙河校区主楼C座826会议室

For decades, RuO2 has been considered as a Pauli paramagnet, until a recent neutron study on a bulk crystal of RuO2 revealed the presence of itinerant, above-room-temperature antiferromagnetism. We studied the magnetic ordering of thin films and  bulk crystals of rutile RuO2 using resonant magnetic x-ray scattering across the RuL2 absorption edge.Combining polarization analysis and azimuthal angledependence of the magnetic Bragg signal, we have established the presence and texture of the collinear antiferromagnetic order in Ruo2 with TNeel > 300K. In additition to revealing a robust antiferromagnetic ground state, the persistence of collinear spin order even in nanometer-thick films paves the way for potential applications of Ruo2 in antiferromagnetic spintronic devices.

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