A broadband perfect field rotator

In this letter, we design a perfect field rotator that is by itself invisible and can rotate the electromagnetic (EM) wave front. The device here is designed for a dielectric background and is composed of merely an inner core with the same dielectric and an array of metal plates embedded in the air. Its broadband functionality is also numerically demonstrated.     

Drinfeld twists of the open XXZ chain with non-diagonal boundary terms

The Drinfeld twists or factorizing F-matrices for the open XXZ spin chain with non-diagonal boundary terms are constructed. It is shown that in the F-basis the two sets of pseudo-particle creation operators simultaneously take completely symmetric and polarization free form. The explicit and completely symmetric expressions of the two sets of Bethe states of the model are obtained.     

Scalar products of the open XYZ chain with non-diagonal boundary terms

With the help of the F-basis provided by the Drinfeld twist or factorizing F-matrix of the eight-vertex solid-on-solid (SOS) model, we obtain the determinant representations of the scalar products of Bethe states for the open XYZ chain with non-diagonal boundary terms. By taking the on shell limit, we obtain the determinant representations (or Gaudin formula) of the norms of the Bethe states.     

自由边界双原子链的晶格振动

指出双原子的晶格振动分为声学支和光学支是由于采用循环边界条件所造成的结果，若采用自由边界条件，则模花样和振动频谱完全不同，这时只能分为低频支，中频支和高频支。     

Specific heat of the anisotropic rigid rotator

The exact (numerical) thermal evolution of the specific heatC of the single anisotropic (not necessarily equal inertial momentaI _x I _y I _xy andI ₂) quantum rigid rotator is calculated. For values ofI _xy /I _z low enough,C presents an unexpectedly high maximum; for sufficiently high values ofI _xy /I _z a second peak emerges. Also a quite rich T0 asymptotic behavior is exhibited.     

The periodically kicked rotator: Recurrence and/or energy growth

We explore the properties of the quantum kicked rotator, its classical equivalent being the standard map. Its behavior, as found by computer studies, depends very much on the strength of the external forcing. At low strength it is seemingly recurrent in the sense of Hogg and Huberman. However, its energy increases with time at large forcings. For quantum systems, a unitary map defines the evolution over one period of time. The spectrum of this map in an infinite space does not seem to change continuously when one approaches the ratio of the frequencies of the external and of the unperturbed system by rational approximations of the golden mean.     

一种基于超材料的宽带、反射型90°极化旋转体设计

根据各向异性媒质理论, 设计了一种宽带、反射型超材料极化旋转体, 能够将线极化波极化方向旋转90°, 极化转化率大于90%的工作带宽为5.5–14.5 GHz. 该极化旋转体由两层介质板、金属双开口谐振环和金属底板周期排列构成, 具有各向异性的特点, 单元两对角线方向的电场分量反射系数相同, 反射相位相差180°, 导致其极化旋转特性. 利用表面电流分布图, 分析不同极化波入射时该极化旋转体的谐振状态, 实验和仿真结果符合较好. 该极化旋转体在新型天线设计和隐身技术等方面具有广阔的应用前景.     

XXZ chain with a boundary

The XXZ spin chain with a boundary magnetic field h is considered, using the vertex operator approach to diagonalize the hamiltonian. We find explicit bosonic formulas for the two vacuum vectors with zero particle content. There are three distinct regions when h ⩾ 0, in which the structure of the vacuum states is different. Excited states are given by the action of vertex operators on the vacuum states. We derive the boundary S-matrix and present an integral formula for the correlation functions. The boundary magnetization exhibits boundary hysteresis. We also discuss the rational limit, the XXX model.     

利用量子几何相位制作光纤偏振旋转器

利用光纤中的量子几何相位(又称Berry相位),制作了单模光纤的线偏振光偏振面旋转器,并对器件进行了测量.实验数据表明,这种光纤偏振旋转器对光偏振面的旋转基本符合理论预计.对偏差进行处理后得到修正的定标公式,可更精确地反映出此光纤偏振旋转器的特性.     

Dynamics of Bose-Einstein condensates with atomic pumping and dissipative processes

In the dynamics of condensed systems described by a nonconservative non-linear Schrödinger equation, we investigate numerically the role of atomic feeding and inelastic collisions where dipolar relaxation is the dominant process. By analyzing the range of possible values of the nonconservative parameters to have stable (or unstable) solutions, we verify that spatio-temporal chaos patterns, known for attractive two-body systems due to collapsing effects, can also occur in the repulsive case when the term corresponding to the linear atomic feeding dominates the nonconservative contributions.     

Breakdown of the chain of ring vortices in a transitional boundary layer

A large number of experiments have been devoted to the study of the generation and development of the high-frequency structures, i.e. the chain of ring-like vortices and breakdown of the chain of ring-llke vortices, to the investi-gation of their relevance to laminar-turbulent transition in a boundary layer flow; however, the origins of turbulence via the process of flow randomization are still not well understood. For this reason a detailed experiment was performed to document the important shape and configuration of the late-stage transitional structures and to investigate some of the still insufficiently understood mechanisms of flow randomization.     

Dynamics of a dissipative two level system

We consider the tunneling of a particle in a symmetric double well, which is coupled to its environment in a way, that classically corresponds to a damping constant γ. In the two lowest level subspace, this is described by a spin-boson model with a finite density of zero energy excitations. A relaxation kernel method is applied to calculate the low temperature, low frequency static and dynamical susceptibility. In particular we determine the average tunneling frequency, which is equivalent to the rate for the destruction of phase coherence. For weak damping this is shown to be finite in the limitT→0, whereas for large γ it vanishes with a power low inT. AtT=0 the two regimes are separated by a phase boundary, dividing regions with finite or zero effective tunnel splitting. We discuss the application of the model to the dynamics of flux states in SQUID's and also to paraelectric impurities.     

Frequency-selective microwave polarization rotator using substrate-integrated waveguide cavities

A frequency selective polarization rotator that can rotate the polarization angle of an incident electromagnetic wave at the microwave frequency by 45 is presented. The polarization rotator is based on a two-dimensional periodic array of substrate integrated waveguide cavities, realizing the polarization rotation by coupling the input signal to the output wave through three metallic slots. Two layers of frequency selective surfaces are cascaded by substrate and form the polarization rotator. A vertical slot on the top layer is used to select the horizontal polarization from the incident wave, the vertical and the horizontal slots on the bottom layer are, respectively, used to obtain horizontally and vertically polarized outgoing waves. The two orthogonal outgoing waves are combined to result in the 45~ polarized wave. Both full wave simulation and experimental measurement are carried out, together validating the proposed method.     

Reflection K-matrices of the 19-vertex model and XXZ spin-1 chain with general boundary terms

We derive and classify all solutions of the boundary Yang-Baxter equation (or the reflection equation) for the 19-vertex model associated with . An integrable XXZ spin-1 chain Hamiltonian with general boundary interactions is also obtained.     

Detecting cracks in a longitudinally vibrating beam with dissipative boundary conditions

This paper focuses on detecting a small open crack in an axially vibrating beam with viscous boundary conditions by using non-destructive dynamical measurements. The damage is simulated by an equivalent linear elastic spring. It is shown that the measurement of the changes in a suitable pair of eigenvalues leads to the solution of the diagnostic problem, namely identification of crack location and severity. Results apply to uniform beams under various sets of boundary conditions.     

An upper bound for the ground-state energy of an antiferromagnetic chain with next-nearest-neighbor interaction

A trial function for the ground state of the antiferromagnetic linear chain leads to an equation for an upper bound of the ground-state energy per spin. This equation is solved exactly.