Dynamics of an Orientational-Kink Pair in a Hydrogen-Bonded Chain in an External Field

We discuss dynamic properties of an orientational-kink pair in hydrogen-bonded chains in the presence of an external force and damping, based on a new two-component soliton model. We study the scattering of an electromagnetic wave by an orientational-kink pair. Finally, we find the expressions of the scattering cross-section of an orientational-kink pair for an electromagnetic wave and the mobility of the orientational-kink pair.     

On the analogy between the classical wave optics and the quantum wave phenomena

A striking correspondence between the effects of an auxiliary-mode-assisted transfer of light power between two waveguides and an auxiliary-state-assisted transfer of an electron between two quantum dots is highlighted by the example of an exactly solvable model.     

Teleportation of a multiqubit state by an entangled qudit channel

We investigate the problem of teleportation of an M-qubit state by using an entangled qudit pair as a quantum channel and show that the teleportation of a multiparticle state can correspond to the teleportation of a multi-dimensional state. We also introduce a quantum-state converter composed of beamsplitter arrays, on/off-detectors and cross-Kerr couplers and demonstrate that the state conversion from an M-qubit to an N-dimensional qudit and vice versa can be implemented with this converter, where N=2^M. Based on this, an experimentally feasible scheme for the teleportation of an M-qubit via an entangled N-level qudit pair channel is proposed.     

Generalized tensor ABCD law for an elliptical Gaussian beam passing through an astigmatic optical system in turbulent atmosphere

The propagation of an elliptical Gaussian beam (EGB) through an astigmatic ABCD optical system in a turbulent atmosphere is investigated. An analytical formula for the average intensity of an EGB and a generalized tensor ABCD law for the generalized complex curvature tensor are derived. As an application example, we derived an analytical formula for the average intensity of an elliptical flat-topped beam propagating through an astigmatic ABCD optical system in a turbulent atmosphere. As a numerical example, the focusing properties of an EGB focused by a thin lens in a turbulent atmosphere are studied. It is found that the focused beam at the focal plane becomes a circular Gaussian beam when the atmospheric turbulence is strong enough, and the beam width of the circular Gaussian beam is determined by atmospheric turbulence strength, focal length of the thin lens, and wavelength of the initial beam but is independent of the initial beam widths (i.e., initial intensity distribution).     

Calculation of phonon life time in amorphous solids

We present the calculation of phonon life time at low frequencies in an amorphous solid, which is assumed to be characterized by an elasticity that exhibits spatial fluctuation. Thermodynamic Green’s function method is used to compute phonon self-energy, and an iterative method is devised to obtain an improvement upon the first order perturbation calculation. The elasticity correlation is taken to be an exponentially falling function of distance. We obtain an inverse life time that varies as the fourth power of phonon frequency for small values of the latter, and whose frequency-dependence becomes weaker and weaker as the frequency increases.     

Anisotropic Bianchi-I universe with phantom field and cosmological constant

We study an anisotropic Bianchi-I universe in the presence of a phantom field and a cosmological constant. Cosmological solutions are obtained when the kinetic energy of the phantom field is of the order of anisotropy and dominates over the potential energy of the field. The anisotropy of the universe decreases and the universe transits to an isotropic flat FRW universe accommodating the present acceleration. A class of new cosmological solutions is obtained for an anisotropic universe in case an initial anisotropy exists which is bigger than the value determined by the parameter of the kinetic part of the field. Later, an autonomous system of equations for an axially symmetric Bianchi-I universe with phantom field in an exponential potential is studied. We discuss the stability of the cosmological solutions.      

A Simple Method for Measuring the Q Value of an NMR Sample Coil

A simple method for measuring the Q (quality factor) value of an NMR sample coil based on an impedance matching principle is described. This method has the advantage of utilizing a signal generator and reflection coefficient bridge rather than an expensive high-frequency Q meter and offers an alternative means of measuring the Q value of an NMR sample coil or any other radio frequency coil.     

New mechanism of formation of virtual surface magnetic polaritons

By using an easy-axis antiferromagnetic material as an example, the conditions are found under the fulfillment of which, the quadratic magneto-optical interaction in an external dc electric field perpendicular to the easy axis gives rise to the formation of a new type of virtual surface magnetic TM polaritons at the interface both between an antiferromagnet and an ideal metal and between an antiferromagnet and vacuum.     

利用共焦扫描显微术和变迹术相结合实现光学超分辨

运用适当形式匠光瞳滤波器民成像系统点振响应的分布，歙 具心于冲击函数的形式，这样就有可能实现光学超分辨，但变迹术的运用往往会因其强烈的旁瓣效应而导致成像系统对比度的急剧下降。本文提出的共焦型超分辨方案则能有效地抑制上述旁瓣。此外，本文学进一瞠提出了实现三维光学超分辨手理论框轲。     

强短脉冲辐照叠加态原子增强阿秒脉冲强度

采用强短激光脉冲辐照叠加态原子提高孤立阿秒脉冲的强度。数值研究表明,与强短脉冲 (脉冲宽度只有几个光学周期的超短脉冲）辐照基态原子获得孤立阿秒脉冲相比,采用叠加 态原子的方案不仅同样可以获得孤立的阿秒脉冲,而且阿秒脉冲的强度得到显著增强。     

New electrostatic cylindrical energy analyzer

The focusing properties of an ideal cylindrical field in full relativistic field have been investigated for charged particles originating from an extended source and an analytical solution for the equations of motion has been provided. This focusing system can be used for production of electrostatic energy analyzer provided surface analysis from an extended area.     

带虚设层的抗反射结构导模共振滤波器设计与分析

提出带虚设层的抗反射导模共振滤波器结构及设计方法,该方法适用于任意角度入射带虚设层的抗反射结构导模共振滤波器设计与分析.得到带虚设层的导模共振滤波器抗反射结构所满足的关系式.指出在维持虚设层光学厚度不变的情况下,可以通过不同选材,在低反射旁带中实现等带宽不同波长的选择.此外,由于结构的抗反射特性在低角范围内具有较大的角度容差,改变入射角,可以实现滤波波长及光谱带宽在宽光谱范围内的准线性可调谐.     

Smoothing of an atomically rough vicinal surface – STM observation and MC simulation

Smoothing of an atomically rough vicinal surface of SrTiO₃ is studied by scanning tunneling microscope (STM) observation and by Monte Carlo (MC) simulation. A complex step pattern that resembles a two-dimensional phase separation pattern is observed on the surface. Analysis of the step pattern during annealing obtained by the STM in comparison with the MC simulation reveals an asymmetry of the relaxation pattern between islands and holes. The asymmetry is attributed to the difference of the mobility of an adatom and an atomic hole, and the asymmetry is enhanced by the step edge diffusion barrier. Values of an effective bond energy and an effective diffusion barrier as well as the surface diffusion coefficient are deduced from the relaxation pattern.     

Comparison of nitride-based dual-wavelength light- emitting diodes with an InAlN electron-blocking layer and with p-type doped barriers

The advantages of nitride-based dual-wavelength light-emitting diodes (LEDs) with an InAlN electron blocking layer (EBL) are studied. The emission spectra,carrier concentration in the quantum wells (QWs),energy band and internal quantum efficiency (IQE) are investigated. The simulation results indicate that an LED with an InAlN EBL performs better over a conventional LED with an AlGaN EBL and an LED with p-type-doped QW barriers. All of the advantages are due to the enhancement of carrier confinement and the lower electron leakage current. The simulation results also show that the efficiency droop is markedly improved and the luminous intensity is greatly enhanced when an InAlN EBL is used.     

卡塞格林望远系统与激光束参数匹配

 在激光工程系统中,把卡塞格林望远系统等效为一个扩束器和环形光阑的组合形式,研究了激光束的光腰半径与卡塞格林望远系统的参数匹配问题。推导出光束扩束后通过环形光阑衍射的场分布解析表达式,并由此数值计算了由环形光阑引起的能量损失,以及光束扩束后光腰半径与环形光阑外径的比值K对Strehl比的影响。结果表明,在卡塞格林望远系统参数确定的条件下,存在最佳比值K,使损失能量最小,并可以获得较高的Strehl比,得到最大的峰值光强。     

First-principles study of the influences of oxygen defects upon the electronic properties of Nb-doped TiO_2 by GGA + U methods

The influence of oxygen defects upon the electronic properties of Nb-doped TiO2has been studied by using the general gradient approximation(GGA)+U method. Four independent models(i.e., an undoped anatase cell, an anatase cell with a Nb dopant at Ti site(NbTi), an anatase cell with a Nb-dopant and an oxygen vacancy(NbTi+VO), and an anatase cell with a Nb-dopant and an interstitial oxygen(NbTi+Oi)) were considered. The density of states, effective mass, Bader charge, charge density, and electron localization function were calculated. The results show that in the NbTi+VOcell both eg and t2glevels of Ti 3d orbits make contributions to the electronic conductivity, and the oxygen vacancies(VO) collaborate with Nb-dopants to favor the high electrical conductivity by inducing the Nb-dopants to release more excess charges. In NbTi+Oi, an unoccupied impurity level appears in the band gap, which served as an acceptor level and suppressed the electronic conductivity. The results qualitatively coincide with experimental results and possibly provide insights into the preparation of TCOs with desirable conductivity.     

Atomic dipole traps with Amplified Spontaneous Emission: A proposal

We propose what we believe to be a novel type of optical source for ultra-cold atomic Far Off-Resonance optical-dipole Traps. The source is based on an Erbium Amplified Spontaneous Emission (ASE) source that seeds a high power Erbium Doped Fiber Amplifier. The main interest of this source is its very short coherence length, thus allowing an incoherent superposition of several trapping beams without any optical interference. The behavior of the superimposed beams is then a scalar sum greatly simplifying complex configurations. As an illustration, we report an estimation of the intensity noise of this source and an estimation of the additional atomic heating rate for an evaporative cooling experiment application. They are both found to be suitable for cold atoms experiments.     

Magnetic behavior of a nano-disk constrained in an antiferromagnetic substrate

In this work we report a numerical Monte Carlo study of the behavior of a magnetic nano-disk put over an antiferromagnetic substrate. Three approaches were considered for describe the substrate: (1) A stacked antiferromagnetic configuration, (2) an Ising like arrangement and (3) Heisenberg like spins. For the Heisenberg case we still have considered an easy-plane and an easy-axis symmetry of the substrate. The hysteresis loop for the nano-disk is obtained by considering the three cases. The signature of the vortex in the nano-disk appears as small jumps in the hysteresis curve. Exchange bias effects are observed since the substrate has an easy axis symmetry.     

稳像光学系统设计

重点沦述光学稳像的光学原理,并引用具体的平面反射镜作为光学补偿元件(也就是光稳元件)的稳像方式加以阐述,由此导出倒像系统和正像系统达到相对稳像和绝对隐像时补偿角与扰动角之间的关系式。论述采用会聚光路稳像时由棱镜的微量转动而达到绝对稳像时棱镜转动中心的求法。论述光稳元件兼作转像棱镜时光稳元件的有效孔径与转功中心和棱镜位置的关系。     

无障板圆形活塞换能器的辐射阻抗*

辐射阻抗是换能器的最重要辐射声场特性参数之一,影响着换能器的谐振频率、频带宽度、效率以及辐射声功率等。经典声学理论用一阶贝塞尔函数和斯特鲁夫函数给出了圆形活塞换能器辐射阻抗的数学表达式,但仅适用于无限大障板条件。该文用ANSYS有限元软件计算了无障板圆形活塞换能器的辐射阻抗,给出了数值解结果,通过与无限大障板条件下的理论结果相比较,显示了二者之间的偏离情况,尤其是在低频时差异显著。为了借助MATLAB工具模拟无障板圆形活塞换能器的辐射阻抗,并给出较准确的数学表达,选择了一系列初等函数以及它们的复合函数进行曲线拟合,最终给出了辐射阻和辐射抗关于ka的函数表达式,在ka值从0.08到20范围内与有限元计算结果很好吻合。