First‑principles study on electronic structure,optical and magnetic properties of rare earth elements X(X=Sc,Y,La,Ce,Eu)doped with two‑dimensional GaSe

The electronic structure,magnetic,and optical properties of two-dimensional(2D)GaSe doped with rare earth elements X(X=Sc,Y,La,Ce,Eu)were calculated using the first-principles plane wave method based on den-sity functional theory.The results show that intrinsic 2D GaSe is a p-type nonmagnetic semiconductor with an indi-rect bandgap of 2.6611 eV.The spin-up and spin-down channels of Sc-,Y-,and La-doped 2D GaSe are symmetric,they are non-magnetic semiconductors.The magnetic moments of Ce-and Eu-doped 2D GaSe are 0.908μ_(B)and 7.163μ_(B),which are magnetic semiconductors.Impurity energy levels appear in both spin-up and spin-down chan-nels of Eu-doped 2D GaSe,which enhances the probability of electron transition.Compared with intrinsic 2D GaSe,the static dielectric constant of the doped 2D GaSe increases,and the polarization ability is strengthened.The ab-sorption spectrum of the doped 2D GaSe shifts in the low-energy direction,and the red-shift phenomenon occurs,which extends the absorption spectral range.The optical reflection coefficient of the doped 2D GaSe is improved in the low energy region,and the improvement of Eu-doped 2D GaSe is the most obvious.

Scattering Relations for Two-Dimensional Electromagnetic Waves in Chiral Media

We consider the scattering of time-harmonic plane waves by an infinitely long penetrable chiral cylinder. The electromagnetic scattering problem is reduced to a transmission problem for a system of two-dimensional Helmholtz equations. We prove the classical reciprocity principle, a general scattering theorem and an optical theorem in R2. Using Herglotz wave functions we define the corresponding far field operator. Applying the general scattering theorem useful relations are proved for the reconstruction of the scatterer. We also prove that for real chirality measure of the penetrable scatterer the far field operator has a countable number of eigenvalues which lie on a circle.

First-principle study of puckered arsenene MOSFET

Two-dimensional material has been regarded as a competitive silicon-alternative with a gate length approaching sub-10 nm,due to its unique atomic thickness and outstanding electronic properties.Herein,we provide a comprehensively study on the electronic and ballistic transport properties of the puckered arsenene by the density functional theory coupled with nonequilibrium Green’s function formalism.The puckered arsenene exhibits an anisotropic characteristic,as effective mass for the electron/hole in the armchair and zigzag directions is 0.35/0.16 m0 and 1.26/0.32 m0.And it also holds a high electron mobility,as the highest value can reach 20045 cm2V–1s–1.Moreover,the puckered arsenene FETs with a 10-nm channel length possess high on/off ratio above 105 and a steep subthreshold swing below 75 mV/dec,which have the potential to design high-performance electronic devices.Interestingly,the channel length limit for arsenene FETs can reach 7-nm.Furthermore,the benchmarking of the intrinsic arsenene FETs and the 32-bit arithmetic logic unit circuits also shows that the devices possess high switching speed and low energy dissipation,which can be comparable to the CMOS technologies and other CMOS alternatives.Therefore,the puckered arsenene is an attractive channel material in next-generation electronics.

Quantum correlation enhanced bound of the information exclusion principle

We investigate the information exclusion principle for multiple measurements with assistance of multiple quantum memories that are well bounded by the upper and lower bounds.The lower bound depends on the observables'complementarity and the complementarity of uncertainty whilst the upper bound includes the complementarity of the observables,quantum discord,and quantum condition entropy.In quantum measurement processing,there exists a relationship between the complementarity of uncertainty and the complementarity of information.In addition,based on the information exclusion principle the complementarity of uncertainty and the shareability of quantum discord can exist as an essential factor to enhance the bounds of each other in the presence of quantum memory.

A deterministic method study of the impact of the Pauli principle in double-gate MOSFETs

The Pauli principle is included in a multisubband deterministic solver for two-dimensional devices without approx- imations. The nonlinear Boltzmann equations are treated properly without compromising on accuracy, convergence, or CPU time. The simulation results indicate the significant impact of the Pauli principle on the transport properties of the quasi-2D electron gas, especially for the on state.

Mo_(3)(C_(6)X_(6))_(2)(X=NH,S,O)monolayers:two-dimensional conductive metal-organic frameworks as effective electrocatalysts for the nitrogen reduction reaction

As a constituent element of amino acids,nitrogen plays an important role in nourishing plants,animals and other forms of life.Although the atmosphere is rich in nitrogen gas(N_(2)),the highly inert N≡N bond makes it difficult for most organisms to directly utilize N_(2).The supply of nitrogen in the biological chain mainly depends on the slow conversion of N_(2) to ammonia(NH3)by biological nitrogen fixation[1].

Two-dimensional conjugated coordination polymer monolayer as anode material for lithium-ion batteries:A DFT study

Nowadays,lithium-ion batteries(LIBs)play a crucial role in modern society in the aspect of portable electronic devices and large-scale smart grids.However,the current performance of lithium-ion batteries has been unable to meet the growing expectations of society and scientific community.Herein,we have synthetically investigated availability of 2D Ni-TABQ monolayer as anode based on DFT for LIBs applications.Our findings have demonstrated that 2D Ni-TABQ monolayer is a semiconductor with a small band gap of 0.2 eV,which suggest that the electronic property of 2D Ni-TABQ monolayer would take place an evident shift from semiconductor property to metallic property after Li adsorption.Furthermore,we checked the stability of 2D Ni-TABQ monolayer and investigated the viability of exfoliation from bulk multilayer Ni-TABQ to form 2D Ni-TABQ monolayer in the light of exfoliation energy and binding energy.We continuously studied electrochemical properties of 2D Ni-TABQ monolayer with respect of theoretical specific capacity,Li-ion diffusion barriers and open-circuit voltage.During the charging process,2D Ni-TABQ monolayer can achieve a high specific capacity of 722 m Ah/g with an open-circuit voltage range from 1.12 V to 0.22 V.These aforementioned results make the 2D Ni-TABQ monolayer a promising anode for LIBs.

证明负温度存在的一种方法

本文从激光原理入手对负温度的存在进行解释 ,利用熵的概念作出推导。

二维时空熵运动检测中的自适应门限技术

针对图像序列中运动检测门限的选取问题,提出一种基于二维时空熵准则自适应确定检测门限的新方法.将运动检测归结为两个二值划分问题,无需已知背景分布的具体形式和参数,利用二维熵准则自适应确定门限矢量(S,T).并提出一种二维熵门限快速计算方法,利用积分和迭代操作避免二维熵门限求解过程中点的重复计算,将灰度级为N的图像的运算量从O(N4)降低到O(N2).实验结果表明,该方法在目标和背景对比度较低的情况下也可提取出完整的运动目标信息,可实现实时处理.

A new entropic force scenario and holographic thermodynamics

We propose a new holographic program of gravity in which we introduce a surface stress tensor.Our proposal differs from Verlinde's in several aspects.First,we use an open or a closed screen.Second,the temperature is not necessary,but a surface energy density and pressure are introduced.The surface stress tensor is proportional to the extrinsic curvature.Third,the energy we use is Brown-York energy and the equipartition theorem is violated by a non-vanishing surface pressure.We discuss holographic thermodynamics of a gas of weak gravity and find a chemical potential,and then show that Verlinde's program does not lead to reasonable thermodynamics.The holographic entropy is similar to the Bekenstein entropy bound.

Two-dimensional bipolar magnetic semiconductors with high Curie-temperature and electrically controllable spin polarization realized in exfoliated Cr(pyrazine)_(2) monolayers

Exploring two-dimensional(2D)magnetic semiconductors with room-temperature magnetic ordering and electrically controllable spin-polarization is a highly desirable but challenging task for nano-spintronics.Here,through first-principles calculations,we propose to realize such a material by exfoliating the recently synthesized organometallic layered crystal Li0.7[Cr(pyz)_(2)]Cl0.7·0.25(THF)(pyz=pyrazine,THF=tetrahydrofuran).The feasibility of exfoliation is confirmed by the rather low exfoliation energy of 0.27 J m^(−2),even smaller than that of graphite.In exfoliated Cr(pyz)_(2)monolayers,each pyrazine ring grabs one electron from the Cr atom to become a radical anion,and then a strong d-p direct-exchange magnetic interaction emerges between Cr cations and pyrazine radicals,resulting in room-temperature ferrimagnetism with a Curie temperature of 342 K.Moreover,the Cr(pyz)_(2)monolayer is revealed to be an intrinsic bipolar magnetic semiconductor where electrical doping can induce half-metallic conduction with controllable spin-polarization direction.

W纠缠辅助下的熵测不准关系

利用弱测量与反弱测量技术,研究了基于W纠缠辅助的熵测不准关系在振幅阻尼噪声下的演化行为.分别对单粒子和双粒子经历噪声的情况进行了模拟计算,发现弱测量与反弱测量技术对双粒子经历噪声的纠缠恢复优于单粒子噪声情况.在双粒子噪声情况下,2个不对易的力学量在同一个体系中的测不准量会明显减少,计算发现该测不准量与弱测量和反弱测量强度、阻尼衰减系数等因素有关.阻尼衰减系数在一定的范围内,弱测量与反弱测量技术有效地提高了W纠缠态抵御噪声的能力,本文给出了关于不确定量更紧的束缚.

量子计算与不确定性原理

对量子计算的计算潜力的高度期望源于量子力学的各种特性,如叠加原理、纠缠现象、破坏性和建设性的量子干扰。相对于经典计算,量子计算具有某些假定的优势,例如量子算法的运行速度比经典算法快;但另一方面却似乎存在影响经典算法但不影响量子算法的障碍,障碍之一是传统上归因于Werner Heisenberg的两个不确定性原理。Heisenberg最初制定的不确定性原理涉及用于测量量子系统的非量子仪器必然会对该系统造成影响。这个原理与其后来的发展有所不同,因为后来发现的不确定性所假定的是不交换可观察量在测量方面存在固有的不能精确测量的特性。在目前的技术发展状况以及当前对量子力学的形式表述与诠释的情况下,这两种不确定性皆有可能对量子计算的速度造成不良影响。近年来,针对这两种不确定性原理有了新的研究成果:1)Ozawa对Heisenberg原理提出了修改,将两种不确定性纳入其内进行并列考虑,从而可以减小Heisenberg原理的不确定性程度;2)在考虑到熵不确定性的情况下,Heisenberg不确定性可被视为Hirschmann不确定性的下界,因此除了在测量上的不确定性之外,量子计算还必须考虑来自其他如信息学的不确定性因素。

f(R) gravity and Maxwell equations from the holographic principle

Extending the holographic program of our previous work,we derive f(R) gravity and the Maxwell equations from the holographic principle,using time-like holographic screens.We find that to derive the Einstein equations and f(R) gravity by a natural holographic approach,the quasi-static condition is necessary.We also find the surface stress tensor and the surface electric current,surface magnetic current on a holographic screen for f(R) gravity and Maxwell's theory,respectively.

Asymptotic behavior of estimators of entropic risk measures under asymmetric Laplace law

In this paper,we study several asymptotic behaviors of the estimators of convex and coherent entropic risk measures.First,the moderate deviation principles of the estimators are given.Second,the central limit theorems of the estimators are given.Finally,several simulation results are given to support our main conclusions.

线性正则变换域Wigner-Ville分布的熵不确定性原理

针对线性正则变换相关的不确定性原理的研究问题,本文得到线性正则变换域Wigner-Ville分布的熵不确定性原理.根据线性正则变换的性质与特点,得到线性正则变换域的Pitt不等式,根据此不等式进一步得到了线性正则变换域Wigner-Ville分布的熵不确定关系式.所得到结果可以看作是经典熵不确性关系式在线性正则变换域的广义形式,为深入研究线性正则变换的理论及应用奠定良好的基础.

On the Far Field Pattern for Acoustic Scattering by a Piecewise Homogeneous Obstacle in Two Dimensions

A time-harmonic plane acoustic wave is scattered by a piecewise homogeneous obstacle with a penetrable or impenetrable core. We construct in the close form an integral representation for the far field pattern in which we have incorporated the physical and geometrical characteristics of the scatterer. Through this representation, we obtain the far field pattern for this scatterer. We prove scattering relations between the far field patterns of two scattering problems due to two distinct incident waves on the same scatterer. In particular, we prove reciprocity and general scattering theorems. The optical theorem, connecting the total power that the scatterer extracts from the incident plane wave either by radiation or by absorption with the corresponding far field pattern of an incident plane wave, is recovered as a corollary of the general scattering theorem. Moreover, if we consider incident waves to be both a plane and a spherical, we derive a mixed reciprocity theorem. We define the corresponding far field operators and using these relations, we prove some properties that can be used for solving inverse scattering problems.

Uniform Asymptotics for Finite-Time Ruin Probabilities of Risk Models with Non-Stationary Arrivals and Strongly Subexponential Claim Sizes

This paper considers the one-and two-dimensional risk models with a non-stationary claim-number process.Under the assumption that the claim-number process satisfies the large deviations principle,the uniform asymptotics for the finite-time ruin probability of a one-dimensional risk model are obtained for the strongly subexponential claim sizes.Further,as an application of the result of onedimensional risk model,we derive the uniform asymptotics for a kind of finite-time ruin probability in a two dimensional risk model sharing a common claim-number process which satisfies the large deviations principle.

量子信息物理基础研究进展

量子力学与信息论的结合产生了量子信息科学,近来量子信息领域的发展又反过来促进了量子物理的发展.本文综述了近几年量子信息物理基础研的一些进展,包括:量子关联的概念与应用,缠辅助的熵的不确定关系和开放量子系统环境的控制及Non-Markovian性的定量研进展.