当手性光遇上手性物质——光非互易与光隔离 | 本周物理学讲座

来源：中国物理学会期刊网

1当手性光遇上手性物质——光非互易与光隔离

报告人：夏可宇，南京大学

时间：6月20日（周四）10:00

单位：清华大学

地点：物理系理科楼C302

光隔离在激光防护、集成光学和量子信息处理中有重要应用。报告将介绍 基于手性腔和波导量子电动力学原理的几种光隔离器和环形器。（1）利用单个原子与手性回音壁模式光学微腔和手性光波导非对称耦合，构建无磁场单光子隔离器和环形器。提出的方案被维也纳量子科技中心实验实现。（2）芯片可集成单光子隔离器，将基于原子——光手性耦合的单光子隔离带宽提高了三个量级。（3）利用热原子系综与环形腔强耦合时微观热运动引起的多普勒频移诱导原子手性极化，并实验演示了常温非互易光传输和光隔离。（4）通过热原子系统构建手性交叉克尔光学非线性，突破了非线性光隔离中的动态互易限制，获得了常温光隔离和光环形器。研究成果有望在量子信息处理得到广泛应用。

2Hidden Analytic Structure for Two-Loop Higgs Amplitudes

报告人：杨刚，中科院理论所

单位：清华大学
时间：6月18日（周二）10:30

地点：物理系理科楼B315

We compute the two-loop Higgs plus three partons amplitudes with high dimensional operators in Higgs effective theory. This provides the two-loop S-matrix elements for the top mass corrections for Higgs plus a jet production at LHC. The results take remarkably simple analytic form. In particular, the maximally transcendental part (functionally the most complex part) presents hidden relations and universal structure. In this talk, I will give an introduction to the related background and also explain the method used to obtain the results.

3基于LSTM循环神经网络的高能物理数据热度预测

报告人：程振京

时间：6月18日（周二）15:00

单位：中科院高能物理所

地点：计算中心二楼会议室

高能物理计算是典型的数据密集型计算，每年需要分析PB级的海量物理数据，对数据访问性能有着越来越高的要求。构建统一命名空间的分级存储系统方案已经被广泛采用。一般根据访问热度不同将数据存储于不同性能、不同价格的存储设备上。当数据热度变化时，再将数据迁移至合适的存储层级。目前数据热度预测广泛采用基于人工经验的启发式算法，由于不同用户计算模式的差异，预测准确率较低。提出了一种借助LSTM深度学习算法，基于文件访问特征预测未来访问热度的方法，作为分级存储中数据迁移的依据。以高能物理实验LHAASO的真实数据为例做了对比测试，结果表明，在相同测试条件下，与已有预测模型相比，该模型具有更高的预测精度和更强的适用性。

4Multilayer Multiconfiguration Time-Dependent Hartree Theory

报告人：Haobin Wang，University of Colorado Denver

时间：6月18日（周二）15:30

单位：北京师范大学

地点：物理楼106

The multilayer multi-configuration time-dependent Hartree (ML-MCTDH) theory is a particularly powerful tool to simulate quantum dynamics for large systems. This rigorous quantum approach is based on an efficient representation of the functional in a time-dependent variational calculation, which recursively expand the wave function in several (or many) dynamically contracted layers. Mathematically, the expansion is equivalent to the hierarchical Tucker tensor decomposition and in fact it is the first practical appearance of the H-Tucker form, although the latter usually employs a binary tree structure. A special skewed tree form is called tensor train in mathematics and matrix product states in physics. In this talk I will outline the derivation of the theory, the scaling of the method, and application of the theory to some model reactions that have interesting many-body quantum effects.

5Ultrafast Laser Spectroscopy of Two-Dimensional Materials

报告人：Hui Zhao，University of Kansas

时间：6月18日（周二）15:30

单位：中科院物理研究所

地点：M238会议室

In this seminar, recent studied on optical and electronic properties of two-dimensional materials by ultrafast laser spectroscopy will be presented. Two-dimensional materials, such as graphene, MoS2, WS2, and black phosphorus are promising materials for future electronic and optoelectronic applications. As a powerful experimental method with high time resolution, ultrafast laser spectroscopy has been used to study two-dimensional materials by many groups worldwide. Several topics will be discussed in this seminar. First, we will present studies of nonlinear optical properties of two-dimensional materials, such as second harmonic generation and two-photon absorption. The former allows detection of the crystal orientation and symmetry of two-dimensional monolayers while the latter can measure the optical bandgap of exciton binding energy of two-dimensional materials. Second, transient absorption microscopy technique will be discussed, which has been used to study photocarrier and exciton dynamics. Third, all-optical injection of ballistic currents in ReS2 studies of the ballistic charge transport will be introduced. Fourth, by performing transient absorption measurements with polarization resolution, spin and valley dynamics of excitons will be discussed. Finally, by performing transient absorption measurements with layer selectivity, we revealed ultrafast electron transfer in hetero-materials formed by stacking two or more two-dimensional materials together. These ultrafast laser measurements of two-dimensional materials and their heterostructures revealed fundamental electronic and optical properties of these materials that are important for their applications as new forms of functional materials.

6New pentaquarks at LHCb

报告人：张黎明，清华大学

时间：6月19日（周三）10:00

单位：中科院理论物理所

地点：ITP South (New) Building 6420

In 2015 the LHCb collaboration reported observation of significant J/psi p pentaquark structures in the $\Lambda_b^0 -> J/\psi p K^-$ decay using Run 1 data. This is a major turning point in the exotic baryon spectroscopy. At this seminar, an update on this pentaquark study with full Run 1 and 2 data collected by the LHCb detector will be presented. New pentaquark state and more complex structures are observed. Possible interpretation will be also discussed. 

7The Role of Environment in Radio Galaxies

报告人：Lu Shen，University of California, Davis

时间：6月19日（周三）12:00

单位：北京大学

地点：KIAA 1st meeting room

Using imaging from the Very Large Array at 1.4GHz, I have compiled a large sample of radio galaxies from the Observations of Redshift Evolution in Large Scale Environments (ORELSE) survey, a survey aimed at systematically searching for large-scale structures in the redshift range of 0.6 < z < 1.3. By virtue of multi-wavelength imaging and high quality spectroscopy, as well as a wide dynamic range of environments sampled by this survey, I classified radio galaxies to three types: AGN, Hybrid and Star Forming Galaxies, and further separated them into different environments. In this talk, I will focus on the radio AGN, and, particularly, the possible effect of radio AGN on their neighboring galaxies. After carefully constructing and comparing to non-radio-detected control samples, a possible signature of additional quenching on radio AGN neighbors was found in high density cluster environments. I will discuss scenarios which may possibly explain this signature, including the possible heating of the intracluster medium due to radio AGN activity. Finally, I will discuss a new constraint on the fraction of AGN contribution from Mid- to Far-Infrared wavelength in radio galaxies using CIGALE.  

8Flavor symmetries of neutrinos and their consequences

报告人：Newton Nath，IHEP

时间：6月19日（周三）15:00

单位：中科院理论物理所

地点：ITP South (New) Building 6420 

Symmetry-based studies have been very successful to explain the observed mixing pattern of neutrinos. Among number of such approaches, mu-tau reflection symmetry, which predicts theta_{23}=pi/4, delta=\pm pi/2 together with non-zero theta_{13}, attracts a lot of attention in recent times. In this talk, we will first talk about the importance of such symmetry.  Moreover, as the latest results of the global best-fit value of neutrino oscillation data favor non-maximal values of theta_{23} and delta, we will next proceed to discuss the breaking of such symmetry to address the realistic leptonic mixing patterns. Later, we will discuss the consequences of such symmetry for DUNE. We aim to talk about DUNE's potential to measure the precision of theta_{23} and delta for the given symmetry. In order to understand the realistic leptonic mixing patterns, one can generalize such symmetry. In this context, we will talk about generalized CP symmetries and the capabilities of the DUNE in probing leptonic CP violation within this framework. Finally, we will also discuss the status and prospects of ‘bi-large’ leptonic mixing pattern considering DUNE. 

9Computation Accelerated Design of Materials and Interfaces for Solid-state Batteries

报告人：Yifei Mo，University of Maryland

时间：6月20日（周四）10:30

单位：中科院物理研究所

地点：M楼253会议室

All-solid-state Li-ion battery based on solid electrolytes is a promising next-generation battery technology with high energy density, intrinsic safety, long cycle life, and wide operational temperatures. However, multiple challenges, such as low ionic conductivity of solid electrolytes and poor interfacial compatibility at the solid electrolyte-electrode interfaces, are impeding the development of this new battery technology.

To resolve these materials challenges, we develop and leverage an array of computation techniques to provide unique materials insights into the fundamental materials limitations and to establish general design principles of materials and solid interfaces. Our first-principles atomistic modeling studies reveal the origin of ultra-fast Li+ diffusion in lithium super-ionic conductors. Based on the newly gained understanding, we establish design principles for fast ion-conductor materials, and demonstrate these design principles in the computation discovery and design of new lithium super-ionic conductors. In addition, we developed materials-genome database-enabled computation approach in investigating the compatibility of heterogeneous interfaces between solid electrolytes and electrodes. Key factors affecting the compatibility of the solid electrolyte-electrode interfaces are identified, and interfacial design strategies are proposed from our thermodynamic computation. The demonstrated computation capabilities represent a transferable model in designing new materials and interfaces for emerging technologies.

10Hierarchical Landscape of Hard Disk Glasses

报告人：廖沁怡，University of Science and Technology of China

时间：6月20日（周四）11:00

单位：中科院理论物理所

地点：ITP South (New) Building 6420 

We numerically analyze the landscape governing the evolution of the vibrational dynamics of hard disk glasses as the density increases towards jamming. We find that the dynamics becomes slow, spatially correlated, and starts to display aging dynamics across an avoided Gardner transition, with a phenomenology that resembles three-dimensional observations. We carefully analyze the behavior of single glass samples, and find that the emergence of aging dynamics is controlled by the apparition of a complex organization of the landscape that splits into a remarkable hierarchy of minima as jamming is approached. Our results show that the mean-field prediction of a Gardner phase characterized by an ultrametric structure of the landscape provides a useful description of finite-dimensional systems, even when the Gardner transition is avoided.

11Shape of Higgs Potential at Future Colliders

报告人：于江浩，中科院理论物理研究所

时间：6月20日（周四）14:00

单位：清华大学

地点：物理系理科楼C302

Although Higgs boson has been discovered, but its self-couplings are poorly constrained, which leaves nature of Higgs boson undetermined. Motivated from difference potential than Landau-Ginzburg type, we systematically organize various new physics scenarios, psuedo-Goldstone Higgs, Coleman-Weinberg Higgs and Tadpole-induced Higgs, etc. We find that di-Higgs production at 27 TeV HE-LHC have ability to discriminate different Higgs scenarios, while it is necessary to use three Higgs production at 100 TeV collider to fully determine shape of Higgs potential.

12Gas accretion and the subsequent evolution of disc galaxies

报告人：Jing Wang，KIAA

时间：6月20日（周四）14:00

单位：清华大学

地点：蒙民伟科技南楼S727

We search for footprints of gas accretion in and around HI-rich massive galaxies with data collected in the Bluedisk project. The HI-rich galaxies tend to have an HI-rich environment, suggesting a large-scale fueling. We find the excess HI has two types of radial distributions in HI-rich galaxies, suggesting two types of gas accretion, possibly corresponding to the fountain mechanism and cosmological accretion. We investigate how disk galaxies evolve with the accreted gas. The growth of discs are tightly corelated with the total amount of HI gas, and the effect can extend to large radius, well beyond the disk breaks. Bars drive strong gas inflows and enhance central SFR in most of the barred galaxies, however, they do not always do so even when plenty of HI is available. The details could depend on the radial distribution of HI and dynamical properties of the bars. Finally, the growth of bulges are not directly related with the HI gas, no matter whether they are pseudo or classical, and no matter whether the galaxies are interacting or hosting bars.

13Further insights into box/peanut bulge formation

报告人：Victor Debattista

时间：6月20日（周四）16:00

单位：北京大学

地点：KIAA-PKU Auditorium

I present new observational data on the evolution of box/peanut bulges to redshift 1.  I will discuss evidence in favour of “kinematic fractionation”, the process by which the stellar populations of box/peanut shaped bulges are ordered.  I present new predictions from models that can be used to further test the mechanism.  I also present their dynamical evolution in the space of the dynamical actions, which provides a powerful new method for assigning stellar populations to stellar particles in simulations, with many potential applications.  Using this technique I then demonstrate some new results about the impact of clump formation on the chemistry of the bulge.

14Fracton order: from quantum hard drive to foliated manifold

报告人：Xie Chen，California Institute of Technology

时间：6月20日（周四）16:00

单位：清华大学

地点：理科楼郑裕彤讲堂

One major open problem in quantum information theory is how to build a quantum hard drive, i.e. a quantum mechanical system that can store quantum information reliably for a very long time without active error correction. No completely satisfying solution to this problem has been found, but in the search for possibilities a whole new class of quantum many-body models have been discovered with exotic properties that have never been seen before. This new class of models, dubbed the “fracton” models, host point excitations that cannot move freely, have robust ground state degeneracy that increases with system size, and have unusually slow thermalization dynamics even in the absence of any disorder. In this talk, I will introduce some of the most important fracton models and present a systematic framework for characterizing their universal properties. By realizing that the model properties depend on the foliation structure of the underlying manifold, we are able to reveal the hidden equivalence relation between many seemingly different models and identify the direction of search for new nontrivial features.

15Nitrogen vacancy center in diamond: a nanoscale quantum sensor for high pressure, and a novel platfo

报告人：Chong Zu

时间：6月21日（周五）10:00

单位：北京大学

地点：物理学院中楼215

Recent experimental advances have enabled the control and manipulation of individual quantum mechanical spins in solids. In this talk, I will introduce two directions our group is currently pursuing using nitrogen-vacancy centers in diamond, one of the most promising solid-state quantum defect, (1) by integrate NV centers directly into the diamond anvil cell (DAC), a workhorse for high pressure physics, we demonstrate the versatility of our quantum sensors by imaging both stress fields and magnetism, up to pressures ~30 GPa and for temperatures ranging from 25-340 K. (2) we introduce a novel platform, based upon NV center and surrounding dense P1 centers (substitutional nitrogen defects), to study non-equilibrium quantum spin dynamics. In particular, we show the ability to directly control the disorder strength, the interaction Hamiltonian and the effective P1 density using a combination of static and driven fields. By preparing a low entropy initial state, we probe the nanoscale spin diffusion of P1 centers, ultimately observing the emergence of hydrodynamics. 

16Quest for Nature Fifty Years of Discoveries in High Energy Physics

报告人：韩涛

时间：6月21日（周五）15:00

单位：北京航空航天大学

地点：新主楼会议中心第八会议室

17LHHAASO的进展及其科学问题

报告人：曹臻

时间：6月21日（周五）19:20

单位：中科院理论物理所

地点：Conference room 6620

1.大型强子对撞机上的实验进展

2.认识黑洞的首个直接“视觉”证据

3.现实中的“降维攻击”导致二维拓扑量子物态 | 文小刚点评

4.物理学的忧伤

5.特别二的物理学——节选自《物理学咬文嚼字》彩色四卷本全集

6.晶体几何系列之三：准晶是高维晶体投影的证明

7.物理学交流的语言

8.建好2年多了,FAST干了啥？

9.一场学习革命

10.周光召先生与开放的中科院理论物理所 | 贺周光召先生从事科学事业65周年