Steady-state entanglement and heat current of two coupled qubits in two baths without rotating wave approximation

We study the steady-state entanglement and heat current of two coupled qubits, in which two qubits are connected with two independent heat baths(IHBs) or two common heat baths(CHBs). We construct the master equation in the eigenstate representation of two coupled qubits to describe the dynamics of the total system and derive the solutions in the steadystate with stronger coupling regime between two qubits than qubit–baths. We do not make the rotating wave approximation(RWA) for the qubit–qubit interaction, and so we are able to investigate the behaviors of the system in both the strong coupling regime and the weak coupling regime, respectively. In an equilibrium bath, we find that the entanglement decreases with the bath temperature and energy detuning increasing under the strong coupling regime. In the weak coupling regime,the entanglement increases with coupling strength increasing and decreases with the bath temperature and energy detuning increasing. In a nonequilibrium bath, the entanglement without RWA is useful for entanglement at lower temperatures.We also study the heat currents of the two coupled qubits and their variations with the energy detuning, coupling strength and low temperature. In the strong(weak) coupling regime, the heat current increases(decreases) with coupling strength increasing when the temperature of one bath is lower(higher) than the other, and the energy detuning leads to a positive(negative) effect when the temperature is low(high). In the weak coupling regime, the variation trend of heat current is opposite to that of coupling strength for the IHB case and the CHB case.

EXISTENCE OF SOLUTION AND APPROXIMATE CONTROLLABILITY OF A SECOND-ORDER NEUTRAL STOCHASTIC DIFFERENTIAL EQUATION WITH STATE DEPENDENT DELAY

This paper has two sections which deals with a second order stochastic neutral partial differential equation with state dependent delay. In the first section the existence and uniqueness of mild solution is obtained by use of measure of non-compactness. In the second section the conditions for approximate controllability are investigated for the distributed second order neutral stochastic differential system with respect to the approximate controllability of the corresponding linear system in a Hilbert space. Our method is an extension of co-author N. Sukavanam’s novel approach in [22]. Thereby, we remove the need to assume the invertibility of a controllability operator used by authors in [5], which fails to exist in infinite dimensional spaces if the associated semigroup is compact. Our approach also removes the need to check the invertibility of the controllability Gramian operator and associated limit condition used by the authors in [20], which are practically difficult to verify and apply. An example is provided to illustrate the presented theory.

The scattering states of the generalized Hulthén potential with an improved new approximate scheme for the centrifugal term

This paper finds the approximate analytical scattering state solutions of the arbitrary 1-wave Schrodinger equation for the generalized Hulthen potential by taking an improved new approximate scheme for the centrifugal term. The normalized analytical radial wave functions of the 1-wave SchrSdinger equation for the generalized Hulthen potential are presented and the corresponding calculation formula of phase shifts is derived. Some useful figures are plotted to show the improved accuracy of the obtained results and two special cases for the standard Hulthen potential and Woods-Saxon potential are also studied briefly.

Approximate Analytical Solutions for Scattering States of D-dimensional Hulthen Potentials

Using the exponential function transformation approach along with an approximation for the centrifugal potential, the radial Schr6dinger equation of D-dimensional Hulthen potential is transformed to a hypergeometric differential equation. The approximate analytical solutions of scattering states are attained. The normalized wave functions expressed in terms of hypergeometrie functions of scattering states on the ＂k/2π scale＂ and the calculation formula of phase shifts are given. The physical meaning of the approximate analytical solutions is discussed.

Approximate Quantum State Sharings via Pair of Private Quantum Channels

We investigate a quantum communication protocol, of so-called approximate quantum state sharing (AQSS), that protocol is basically based on pair of private quantum channels. In this paper, we prove that the scheme is secure against any external and internal attacks of wiretapping in principle. Although the protocol leaks small amount of information corresponding to a security parameter , the scheme still preserves its information-theoretic security.

Crossed Beam Experiment on the Validity of Born-Oppenheimer Approximation in Cl(2P)+D2→DCl+D Reaction

The reaction of chlorine atom Cl(2P)(Cl(2P3/2)and Cl^*(2P1/2))with D2 was investigated at collision energy from 4.5 kcal/mol to 6.5 kcal/mol with a high-resolution crossed molecular beam apparatus using the technique of D-atom Rydberg tagging detection.The contribution from the spin-orbit excited reaction Cl^*(2P1/2)+D2,which is prohibited by Born-Oppenheimer(BO)approximation,was observed.Collision-energy dependence of differential cross sections(DCSs)near the backward scattering direction was measured.The BOforbidden reaction Cl^*+D2 was found to be dominant at lower collision energy.As collision energy increases,reactivity of BO-allowed reaction Cl+D2 increases much faster than that of BO-forbidden reaction and becomes dominant at higher collision energy.Our experiment indicates that the additional energy of spin-orbit excitation in Cl^*facilitates BO-forbidden reaction to pass through the barrier at lower collision energy,while BO approximation is still valid at collision energy near and above the reaction barrier.This tendency of reactivity of Cl/Cl^*+D2 is similar to the isotopic reaction of Cl/Cl^*+H2.

光纤孤子的量子特性:压缩态和类薛定谔猫态(Schrdinger-cat-like states)

利用与时间有关的Hartree近似法证明借助非线性Mach-Zehnder干涉仪可以得到光孤子的光子数压缩态<(Δ^N)2>min～<^N>1/3,并且指出在一些特定时刻光纤孤子会呈现出类薛定谔猫态(Schr dinger-cat-likestates)。

Using approximate dynamic programming for multi-ESM scheduling to track ground moving targets

This paper researches the adaptive scheduling problem of multiple electronic support measures(multi-ESM) in a ground moving radar targets tracking application. It is a sequential decision-making problem in uncertain environment. For adaptive selection of appropriate ESMs, we generalize an approximate dynamic programming(ADP) framework to the dynamic case. We define the environment model and agent model, respectively. To handle the partially observable challenge, we apply the unsented Kalman filter(UKF) algorithm for belief state estimation. To reduce the computational burden, a simulation-based approach rollout with a redesigned base policy is proposed to approximate the long-term cumulative reward. Meanwhile, Monte Carlo sampling is combined into the rollout to estimate the expectation of the rewards. The experiments indicate that our method outperforms other strategies due to its better performance in larger-scale problems.

Continuum states of modified Morse potential

Using a proper approximation scheme to the centrifugal term, we study any l-wave continuum states of the Schrodinger equation for the modified Morse potential. The normalised analytical radial wave functions are presented, and a corresponding calculation formula of phase shifts is derived. It is shown that the energy levels of the continuum states reduce to those of the bound states at the poles of the scattering amplitude. Some numerical results are calculated to show the accuracy of our results.

A simplified approximate model of compressible hypervelocity penetration

A simplified approximate model considering rod/target material's compressibility is proposed for hypervelocity penetration.We study the effect of shockwaves on hypervelocity penetration whenever the compressibility of the rod is much larger,analogously,and much less than that of the target,respectively.The results show that the effect of shockwaves is insignificant up to 12 km/s,so the shockwave is neglected in the present approximate model.The Murnaghan equation of state is adopted to simulate the material behaviors in penetration and its validity is proved.The approximate model is finally reduced to an equation depending only on the penetration velocity and a simple approximate solution is achieved.The solution of the approximate model is in agreement with the result of the complete compressible model.In addition,the effect of shockwaves on hypervelocity penetration is shown to weaken material's compressibility and reduce the interface pressure of the rod/target,and thus the striking/protective performance of the rod/target is weakened,respectively.We also conduct an error analysis of the interface pressure and penetration efficiency.With a velocity change of 1.6 times the initial sound speed for the rod or target,the error of the approximate model is very small.For metallic rod-target combinations,the approximate model is applicable even at an impact velocity of 12 km/s.

Research on the Relationship between Density of States and Conducting Properties of Single-walled Carbon Nanotubes

The analytical expression of the electronic density of states (DOS) for single-walled carbon nanotubes (SWNTs) has been derived on the basis of graphene approximation of the energy E(k) near the Fermi level EF. The distinctive properties of the DOS, the normalized differential conductivity and the current us bias for SWNTs are deduced and analyzed theoretically. The singularities in the DOS (or in the normalized differential conductivity) predict that the jump structure of current (or conductance)-bias of SWNTs exists. All conclusions from the theoretical analysis are in well agreement with the experimental results of SWNT's electronic structure and electronic transport. In other words, the simple theoretical model in this paper can be applied to understand a range of spectroscopic and other measurement data related to the DOS of SWNTs.

Generation of Schrdinger cat state of a single trapped cold ion

The fidelity of the generated Schrodinger Cat state （SCS） of a single trapped ion in the Lamb-Dicke approximation is discussed. The results show that the fidelity significantly decreases with the values of Lamb-Dicke parameter η and coherent state amplitude α increasing. For η= 0.20 and α = 3, the typical values of experimental parameters, the fidelity is rather low （3070）. A scheme for generating the SCS is proposed without making the Lamb-Dike approximation in laser-ion interaction, and the fidelity of the generated SCS is about 99% for the typical values of experimental Lamb- Dicke parameters.

Wave Period Distributions in Non-Gaussian Mixed Sea States

The wave period probability densities in non-Gaussian mixed sea states are calculated by utilizing a transformed Gaussian process method. The transformation relating the non-Gaussian process and the original Gaussian process is obtained based on the equivalence of the level up-crossing rates of the two processes. A saddle point approximation procedure is applied for calculating the level up-crossing rates in this study. The accuracy and efficiency of the transformed Gaussian process method are validated by comparing the results predicted by using the method with those predicted by the Monte Carlo simulation method.

Iterative approximate solutions of kinetic equations for reversible enzyme reactions

We study kinetic models of reversible enzyme reactions and compare two techniques for analytic approximate solutions of the model. Analytic approximate solutions of non-linear reaction equations for reversible enzyme reactions are calculated using the Homotopy Perturbation Method (HPM) and the Simple Iteration Method (SIM). The results of the approximations are similar. The Matlab programs are included in appendices.

Transition From Hyper－Chaotic State to Quasi－Steady State in a Spailally Distributed Nonlinear System

The dynamic characteristic in a spatially distributed nonlinear system, a subset of lasers in an array of coupled lasers, has been studied and analysed numerically. The evolution, with the increasing coupling strength,from stable quiescent state to chaotic state, to hyper-chaotic state and, back to quasi-steady state has been observed in this system.

Characteristics Extraction of Vehicle State Information Based on Entropy Calculation

A method of extracting and detecting vehicle stability state characteristics based on entropy is proposed.The vehicle’s longitudinal and lateral dynamics models are established for complex driving and maneuver conditions.The corresponding state observer is designed by adopting the moving horizon estimation algorithm,which realizes the observation of the vehicle stability state considering the global state information.Meanwhile,the Shannon entropy is modified to approximate entropy,and the approximate entropy value of the observed vehicle state is calculated.Furthermore,the optimal controller is designed to further validate the reliability of the entropy value as the reference of control system.Simulation results demonstrate that this method can quickly detect the instability state of the system during the process of vehicle driving,which provides a reference for risk prediction and active control.

覆水情况下沥青路面对905 nm激光的散射特性

以常见的覆水沥青路面为研究对象,利用几何光学光线追踪方法构建了覆水情形下沥青路面激光散射模型,实验验证了该模型的准确性。在此基础上,数值计算分析了不同入射角度下,路面粗糙度、入射光偏振态以及覆水深度等因素对散射光强的影响规律。结果表明,散射光强分布曲线随着表面粗糙程度的增大逐渐趋向于余弦分布,并且当均方根斜率大于0.5时,开始出现后向散射增强趋势。沥青路面在覆水前后的散射特性存在明显差异。覆水后散射光强分布宽度变大、p光布儒斯特角消失,且s、p光峰值差减小。此外,覆水使得路面散射强度在入射光镜面方向产生尖锐高峰,除尖锐高峰之外的光强峰值与覆水前散射强度峰值相比明显降低,约为原峰值的五分之一,且差值随着入射角增大而增大。该研究可为路面状态感知手段以及车载光学传感器的优化提供理论和实验数据支持。

Studies of low-lying states of even-even Xe isotopes within the nucleon pair approximation

We study the relevance of nucleon pairs with higher spins, in addition to spin-zero and spin-two pairs (i.e., S D pairs), in low-lying states of even-even Xe nuclei. By including those higher-spin pairs in our configuration, we recalculate energy level schemes, elec trical quadrupole moments, magnetic moments and electric quadrupole transition rates, for low-lying states of even-even 128-142Xe nuclei. The agreement between our calculated results and the experimental data is substantially improved in comparison with previous studies.

Stochastic approximation with state-dependent noise

The purpose of stochastic approximation (SA) is to find the roots of f(·) or the maximiz-er (minimizer) of L(·) when the unknown function f(·) or L(·) can be observed but with noise. SA is an important tool in dealing with many problems arising from systems and control, whose solutions often rely on convergence of the SA algorithm applied. Here the pathwise convergence of SA algorithms is considered, when the observation noise may depend on state by which we mean those x at which f( x) or L( x) are observed. The conditions imposed on the observation noise are the weakest in comparison with the existing ones. When the algorithm is to find the roots of f(·), the superiority of the condition given in the paper over those used in literature consists in the fact that the present condition is directly verifiable, needless to see the behaviour of the algorithm. When the algorithm is to find the maximizer (minimizer) of L(·), the present conditioin allows the observation noise to depend on the state. The conditions imposed on f(·) and L(·) are truly general: f(·) is required to be measurable and locally bounded if the roots of f(·) are sought, and the gradient of L(·) is required to be locally Lipschitz continuous if the maximizer (minimizer) of L(·) is searched.

数值求解耦合Gross-Pitaevskii方程组基态解的离散归一化梯度流方法

本文提出了一种求解磁场项为常数的耦合Gross-Pitaevskii方程组基态解的数值方法.基于单组分近似理论,本文将方程组的能量函数等价为单组分的能量泛函,然后基于降阶后的能量表达式提出了离散归一化梯度流数值方法.数值算例表明,该方法高效且可靠.