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Standard Embeddings of Smooth Schubert Varieties in Rational Homogeneous Manifolds of Picard Number 1

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Acta Mathematica Sinica,English Series 2018年第3期34卷 466-487页

作者： Shin-Young KIM Kyeong-Dong PARK Department of Mathematics and Statistics Masaryk University Brno Czech center for geometry and physics Institute for Basic Science ( IBS) Pohang Korea

Smooth Schubert varieties in rational homogeneous manifolds of Picard number 1 are horospherical varieties. We characterize standard embeddings of smooth Schubert varieties in rational homogeneous manifolds of Picard number 1 by means of varieties of minimal rational tangents. In particular, we mainly consider nonhomogeneous smooth Schubert varieties in symplectic Grassmannians and in the 20-dimensional F_4- homogeneous manifold associated to a short simple root.

关键词： Smooth Schubert varieties rational homogeneous manifolds variety of minimal rational tangents standard embeddings Cartan-Fubini extension

Controlling the magnetic state of the proximate quantum spin liquid α-RuCl_(3) with an optical cavity

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npj Computational Materials 2023年第1期9卷 265-274页

作者： Emil Viñas Boström Adithya Sriram Martin Claassen Angel Rubio Max Planck Institute for the Structure and Dynamics of Matter Luruper Chaussee 14922761 HamburgGermany Department of physics Stanford UniversityStanfordCA 94305USA Department of physics and Astronomy University of PennsylvaniaPhiladelphiaPA 19104USA center for Computational Quantum physics Flatiron InstituteSimons FoundationNew York CityNY 10010USA

Harnessing the enhanced light-matter coupling and quantum vacuum fluctuations resulting from mode volume compression in optical cavities is a promising route towards functionalizing quantum materials and realizing exotic states of ***,we extend cavity quantum electrodynamical materials engineering to correlated magnetic systems,by demonstrating that a Fabry-Pérot cavity can be used to control the magnetic state of the proximate quantum spin liquidα-RuCl_(3).Depending on specific cavity properties such as the mode frequency,photon occupation,and strength of the light-matter coupling,any of the magnetic phases supported by the extended Kitaev model can be *** particular,in the THz regime,we show that the cavity vacuum fluctuations alone are sufficient to bringα-RuCl_(3) from a zigzag antiferromagnetic to a ferromagnetic *** external pumping of the cavity in the few photon limit,it is further possible to push the system into the antiferromagnetic Kitaev quantum spin liquid state.

关键词： state quantum magnetic

Gravitational Energy-Momentum and Conservation of Energy-Momentum in General Relativity

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Communications in Theoretical physics 2016年第6期65卷 716-730页

作者：吴兆颜 center for Theoretical physics Jilin University

Based on a general variational principle, Einstein–Hilbert action and sound facts from geometry, it is shown that the long existing pseudotensor, non-localizability problem of gravitational energy-momentum is a result of mistaking different geometrical, physical ob jects as one and the same. It is also pointed out that in a curved spacetime, the sum vector of matter energy-momentum over a finite hyper-surface can not be defined. In curvilinear coordinate systems conservation of matter energy-momentum is not the continuity equations for its components. Conservation of matter energy-momentum is the vanishing of the covariant divergence of its density-flux tensor field. Introducing gravitational energy-momentum to save the law of conservation of energy-momentum is unnecessary and improper. After reasonably defining "change of a particle's energy-momentum", we show that gravitational field does not exchange energy-momentum with particles. And it does not exchange energy-momentum with matter fields either. Therefore, the gravitational field does not carry energy-momentum, it is not a force field and gravity is not a natural force.

关键词： pseudotensor non-localizability gravitational energy-momentum energy-momentum conservation

Two-Dimensional Hybrid Model for High-Current Electron Beam Transport in a Dense Plasma

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Plasma Science and Technology 2014年第11期16卷 1007-1012页

作者：曹莉华王欢张华刘占军吴俊峰李百文 Institute of Applied physics and Computational Mathematics HEDPS Center for Applied Physics and TechnologyPeking University

A two-dimensional hybrid code is developed to model the transport of a high-current electron beam in a dense plasma target. The beam electrons are treated as particles and described by particle-in-cell simulation including collisions with the target plasma particles. The background target plasma is assumed to be a stationary fluid with temperature variations. The return current and the self-generated electric and magnetic fields are obtained by combining Amp^re＇s law without the displacement current, the resistive Ohm＇s law and Faraday＇s law. The equations are solved in two-dimensional cylindrical geometry with rotational symmetry on a regular grid, with centered spatial differencing and first-order implicit time differencing. The algorithms implemented in the code are described, and a numerical experiment is performed for an electron beam with Maxwellian distribution ejected into a uniform deuterium-tritium plasma target.

关键词： electron beam transport hybrid simulation energy deposition

Exact results for Wilson loops in orbifold ABJM theory

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Chinese physics C 2016年第8期40卷 20-32页

作者：欧阳昊吴俊宝张甲举 Theoretical physics Division Institute of High Energy PhysicsChinese Academy of Sciences Theoretical physics center for Science Facilities Chinese Academy of Sciences center for High Energy physics Peking University

We investigate the exact results for circular 1/4 and 1/2 BPS Wilson loops in the d = 3 N = 4 super Chern-simons-matter theory that could be obtained by orbifolding Aharony-Bergman-Jafferis-Maldacena （ABJM） theory. The partition function of the Af = 4 orbifold ABJM theory has been computed previously in the literature. In this paper, we re-derive it using a slightly different method. We calculate the vacuum expectation values of the circular 1/4 BPS Wilson loops in fundamental representation and of circular 1/2 BPS Wilson loops in arbitrary representations. We use both the saddle point approach and Fermi gas approach. The results for Wilson loops are in accord with the available gravity results.

关键词： AdS/CFT correspondence Wilson loop Chern-simons theory matrix model

Thermodynamics and microstructures of Euler–Heisenberg black hole in a cavity

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Communications in Theoretical physics 2023年第9期75卷 91-103页

作者： Qin Yu Qi Xu Jun Tao center for Theoretical physics College of PhysicsSichuan UniversityChengdu610065China

Euler–Heisenberg black holes with quantum electrodynamics(QED) correction are embraced by a cavity in this paper, which serves as a boundary of the black hole spacetime and contributes to the equilibrium of the system. We explore the thermodynamic properties of the black hole, including the phase transitions and phase structures. The small/large black hole phase transition occurs for a negative QED parameter, while the reentrant phase transition can be observed for a small positive QED parameter. Then the thermodynamic geometry is investigated to diagnose microscopic interactions of black hole thermodynamic systems. For the reentrant phase transition, the small black holes are dominated by repulsion for the first-order coexistence curve, while the interaction between the small black hole molecules could be attractive or repulsive for the small/large black hole phase transition.

关键词： black hole thermodynamics phase transition microstructure

Microstructure of charged AdS black hole with minimal length effects

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Chinese physics C 2022年第12期46卷 298-311页

作者： Ningchen Bai Aoyun He Jun Tao center for Theoretical physics College of PhysicsSichuan UniversityChengdu 610065China

In this work,the microstructure of charged AdS black holes under minimal length effects is *** study the thermodynamics of black holes in the extended phase space,where the cosmological constant is regarded as the thermodynamic *** modified Hawking temperature and phase transition are obtained based on the generalized uncertainty principle(GUP).Then,using thermodynamic geometry,the microstructure of black holes can be determined by the ratio of the GUP parameter to *** a small ratio,the black hole exhibits the typical RN-AdS microstructure with van der Waals phase transition and repulsive/attractive *** the ratio increases,the reentrant phase transition is observed,and both the repulsion-attraction coexisted and the attraction dominated black holes are *** a large ratio,the black hole behaves like a Schwarzchild-AdS black hole in which neither phase transition nor repulsive interaction are *** results suggest that the GUP effect will reduce the repulsive interaction presented by the charged AdS black hole.

关键词： black hole microstructure generalized uncertainty principle black hole thermodynamics

Holographic Entanglement Entropy: A Topical Review

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Communications in Theoretical physics 2019年第7期71卷 837-852页

作者： Bin Chen Department of physics and State Key Laboratory of Nuclear physics and Technology Peking University Collaborative Innovation center of Quantum Matter center for High Energy physics Peking University

In this topic review,we introduce recent developments on holographic entanglement *** briefly reviewing the basic notions of entanglement in quantum information and quantum field theory,we introduce the RyuTakayanagi’s prescription of computing the entanglement entropy *** review the inequalities on the holographic entanglement entropy,and its derivation from Euclidean *** particular,we discuss its implications in semi-classical AdS3/CFT2 correspondence,and furthermore review the recent studies on the emergence of geometry and gravity from entanglement.

关键词： entanglement entropy gravity holography AdS-CFT correspondence

Thermal analysis and water-cooling design of the CSNS MEBT 324 MHz buncher cavity

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Chinese physics C 2008年第4期32卷 280-284页

作者：刘华昌欧阳华甫 Accelerator center Institute of High Energy PhysicsCAS

At least two bunchers are needed in the 3 MeV H^- Medium Energy Beam Transport （MEBT） line located between RFQ and DTL for the CSNS （China Spallation Neutron Source）. A nose-cone geometry has been adopted as the type of buncher cavity for its simplicity, higher impedance and lower risk of multipacting. By making use of the results got from the simulations on the buncher with two-dimension code SUPERFISH, the thermal and structural analyses have been carried out, the process and results to determine the resulting frequency shift due to thermal and structural distortion of the cavity are presented, the water-cooling channel position and the optimum cooling water temperature as well as the tuning method by adjusting the cooling water temperature when the cavity is out of resonance are also determined through the analyses.

关键词： buncher cavity thermal and structural analysis water-cooling frequency shift