Large Signal Modulation Characteristics in the Transition Regime for Two-State Lasing Quantum Dot Lasers

Large-signal modulation capability, as an important performance indicator, is directly related to the high-speed optical communication technology involved. We experimentally and theoretically investigate the large-signal modulation characteristics of the simultaneous ground-state （GS） and the excited-state （ES） lasing in InAs/OaAs quantum dot laser diodes. The large-signal modulation capability of total light intensity in the transition regime from OS lasing to two-state lasing is unchanged as the bias-current increases. However, GS and ES large-signal eye diagrams show obvious variations during the transition. Relaxation oscillations and large-signal eye diagrams for OS, ES, and total light intensities are numerically simulated and analyzed in detail by using a rate-equation model. The -ndings show that a complementary relationship between the light intensities for OS and ES lasing exists in both the transition regime and the two-state lasing regime, leading to a much smaller overshooting power and a shorter settling time for the total light intensity. Therefore, the eye diagrams of GS or ES lasing are diffuse whereas those of total light intensity are constant as the bias-current increases in the transition regime.

A Deep Two-State Gated Recurrent Unit for Particulate Matter (PM_(2.5)) Concentration Forecasting

Air pollution is a significant problem in modern societies since it has a serious impact on human health and the environment.Particulate Matter(PM_(2.5))is a type of air pollution that contains of interrupted elements with a diameter less than or equal to 2.5 m.For risk assessment and epidemiological investigations,a better knowledge of the spatiotemporal variation of PM_(2.5) concentration in a constant space-time area is essential.Conventional spatiotemporal interpolation approaches commonly relying on robust presumption by limiting interpolation algorithms to those with explicit and basic mathematical expression,ignoring a plethora of hidden but crucial manipulating aspects.Many advanced deep learning approaches have been proposed to forecast Particulate Matter(PM_(2.5)).Recurrent neural network(RNN)is one of the popular deep learning architectures which is widely employed in PM_(2.5) concentration forecasting.In this research,we proposed a Two-State Gated Recurrent Unit(TS-GRU)for monitoring and estimating the PM_(2.5) concentration forecasting system.The proposed algorithm is capable of considering both spatial and temporal hidden affecting elements spontaneously.We tested our model using data from daily PM_(2.5) dimensions taken in the contactual southeast area of the United States in 2009.In the studies,three evaluation matrices were utilized to compare the overall performance of each algorithm:Mean Absolute Error(MAE),Root Mean Square Error(RMSE),and Mean Absolute Percentage Error(MAPE).The experimental results revealed that our proposed TS-GRU model outperformed compared to the other deep learning approaches in terms of forecasting performance.

Einstein Dilemma and Two-State Vector Formalism

In the famous EPR paper published in 1935, Einstein, Podolsky, and Rosen suggested a thought experiment, which later became known as the “EPR experiment”. Using the EPR experiment, they posited that quantum mechanics was incomplete. Einstein, however, was dissatisfied with the EPR paper and published a second work on the EPR experiment, in which he discussed the dilemma of choosing whether quantum mechanics was incomplete or nonlocal. Currently, most physicists choose the nonlocality of quantum mechanics over Einstein’s choice of the incompleteness of quantum mechanics. However, with an appropriate alternate hypothesis, both of these choices can be rejected. Herein, I demonstrate an approach to overcome the Einstein Dilemma by proposing a new interpretation invoked by a new formalism of quantum mechanics known as two-state vector formalism.

Measurement Problem and Two-State Vector Formalism

In this paper, I show that an interpretation of quantum mechanics using two-state vector formalism proposed by Aharonov, Bergmann, and Lebowitz, can solve one of the measurement problems formulated by Maudlin. According to this interpretation, we can simultaneously insist that the wave function of a system is complete, that the wave function is determined by the Schr?dinger equation, and that the measurement of a physical quantity always has determinate outcomes, although Maudlin in his formulation of the measurement problem states that these three claims are mutually inconsistent. Further, I show that my interpretation does not contradict the uncertainty relation and the no-go theorem.

Transfer Matrix Approach for Two-State Scattering Problem with Arbitrary Coupling

The present work deals with the calculation of transition probability between two diabatic potentials coupled by any arbitrary coupling. The method presented in this work is applicable to any type of coupling while for numerical calculations we have assumed the arbitrary coupling as Gaussian coupling. This arbitrary coupling is expressed as a collection of Dirac delta functions and by the use of the transfer matrix technique the transition probability from one diabatic potential to another diabatic potential is calculated. We examine our approach by considering the case of two constant potentials coupled by Gaussian coupling as an arbitrary coupling.

Theoretical Investigation for Two-state Reactivity of CO_2 Hydrogenation Catalyzed by Ru in Gas Phase

Gas-phase CO_2 catalyzed activation hydrogenation by Ru atoms was studied with density functional theory. Based on the structure optimization of different potential energy surfaces,there are two crossing points between singlet and triplet potential energy surfaces and there is a crossing point between quintet and triplet potential energy surfaces in the whole catalytic cycle. Spin transition probabilities in the vicinity of the intersections have been calculated by the Landau-Zener model theory. There are three minimum energy crossing points（MECPs） with strong spin-orbital coupling effect and higher spin transition probability,and all spin inversion occurred in s orbital and different d orbitals of ruthenium,indicating this is a typical two-state reactivity（TSR） reaction. Finally,the lowest energy reaction path is ensured.

Effective Two-State Model and NOON States for Double-Well Bose-Einstein Condensates in Strong-Interaction Regime

The model of double-well Bose-Einstein condensates in the strong-interaction regime is shown to reduceadiabatically to an effective two-state model describing the Rabi oscillations between the two atomic Fock states |N,0〉and |0,N〉,and the NOON states of arbitrary ultracold atoms can therefore be generated periodically from the initialstate of either one of the Fock states.

Low-order harmonic generation of hydrogen molecular ion in laser field studied by the two-state model

The low-order harmonic generation of hydrogen molecular ion interacting with a linearly polarized laser field has been investigated theoretically by using a simple two-state model. The validity of the two-state model is carefully examined by comparing the harmonic spectra of hydrogen molecular ion obtained from this model with those from the three-dimensional time-dependent Schr¨odinger equation. When combined with the Morlet transform of quantum time-frequency spectrum,the two-state model can be used to study the dynamical origin of the low-order harmonic generation of hydrogen molecular ion driven by low-frequency pulses. In addition, some interesting structures of the time profiles for low order harmonics are obtained.

Theoretical study of spin-orbit coupling and intersystem crossing in the two-state reaction between Nb(NH_2)_3 and N_2O

The two-state mechanism of the reaction of Nb(NH2)3 with N2O on the singlet and triplet potential energy surfaces has been investigated at the B3LYP level.Crossing points between the potential energy surfaces have been located using different methods.Analysis of the strain model shows that the singlet state of the four-coordinate(N2O)Nb(NH2)3 complex with N2O bonded via terminal N atom coordination(12) is more stable in the initial stage of reaction,since the bending of the N2O fragment [Edef(N2O) = 86.1 kcal mol-1] results in an energy splitting of the doubly degenerate LUMO;the low-energy LUMO can now strongly couple with the occupied Nb-localized d orbitals,forming a back-bond and transferring charge(q = 0.82 e) from Nb(NH2)3 to the N2O ligand.Going from 32 to 12,the reacting system changes spin multiplicity near the MECP(minimal energy crossing point) region,which takes place with a spin crossing barrier of 9.6-10.0 kcal mol-1.Analysis of spin-orbit coupling(SOC) indicates that MECP will produce a significant SOC matrix element.The value of SOC is 111.52 cm-1,due to the electron shift between two perpendicular φ orbitals with the same rotation direction,and the magnitude of the spin-multi-plicity mixing increases in the small energy gap between high-and low-spin states,greatly enhancing the probability of intersystem crossing.The probabilities of single(P1 ISC) and double(P2 ISC) passes estimated at MECP(SOC = 111.52 cm-1) are approximately 1.17×10-2 and 2.32×10-2,respectively.

Theoretical study of spin-orbit coupling and zero-field splitting in the spin-forbidden two-state reaction between cobaltacyclopentadiene and isocyanate

The two-state reaction mechanism of CpCo(C_4H_4)with isocyanate on the triplet and singlet potential energy surfaces has been investigated at the B3LYP level.A study is described for the computation of spin-orbit coupling of triplet state of the minimal energy crossing point(CP)with their singlet states and of the zerofield splitting(ZFS)parameters of the triplet states,including the full one-and two-electron terms of the BreitPauli Hamiltonian.There are two key crossing points along this two-state reaction pathway.The first crossing point—CP2 exists near^1B.The reacting system will change its spin multiplicity from the triplet state to the singlet state near this crossing region.Although the spin-orbit coupling interaction and ZFS D-tensor of the CP2 region are very strong,the reaction system will occur the reverse intersystem crossing from T_1 to S_0.Therefore,its spin-flip efficiency may be lower.The second crossing point,CP3will again change its spin multiplicity from the singlet state to the triplet state in the Co-Cr bond activation pathway,leading to a decrease in the barrier height of^1TS(CF)from19.5 to 9.5 kcal/mol(1cal=4.182 J),and the efficiency of intersystem crossing from S_0 to T_1 is high because the larger spin-orbit coupling(SOC)matrix elements will result in the overpopulations of the three sublevels of T_1(3.30×10^(-1),3.32×10^(-1),and 3.38×10^(-1),respectively).

一种动态锁定式多星协同任务规划的A2C算法

提出了一种基于强化学习算法的多星协同任务规划方法。该方法将多星协同任务规划视为多个双星协同规划,采用相邻双星锁定的方式来共享双星任务规划结果信息,基于A2C(优势动作评价)强化学习算法对双星任务规划的结果进行再调整。针对多星协同任务规划状态空间复杂且变化的问题,设计了两级状态空间和价值评价函数决策的方法,对强化学习所依赖的状态空间进行维度限制,确保智能体对任务进行调整的过程不影响状态空间维度。算法设计过程考虑了多种约束条件,设置了天气、成像质量和成像优先级等可调参数作为强化学习A2C算法的评价参数,这些可调参数有助于用户自定义决策评价体系。最后,通过仿真验证了算法的可行性。仿真结果表明,该算法多星协同任务规划的组合任务抛弃率小于10%。

基于荷电状态一致性的电池组双层动态均衡方法

针对储能系统中电池组充放电过程中能量利用率以及系统运行安全性较低的问题,提出考虑SOC一致性的电池组双层动态均衡方法。首先,采用耦合电感与Flyback变换器搭建均衡系统双层架构,建立电池组端电压、均衡电流及占空比间的关联特性。为提高电池组的供能可靠性,系统引入故障切除功能,通过改变开关阵列导通状态实现故障电池组的快速切除;其次,考虑增补电池组剩余容量较大问题,利用传统最值法改进的双层极值法,以荷电状态(stage of charge,SOC)作为均衡目标变量,对增补电池组进行快速放电均衡;最后,设计充放电及静置均衡实验,对比传统最值法,分析常态及故障切除后电路的均衡速度与均衡效率。结果表明,提出的双层均衡方法可以将均衡速度提升约10%,且故障切除后电路的均衡效率最高可达95%以上。

二态量子系统准确布居动力学的一类新型相空间表示及其与三角窗函数的关系

二态系统是最简单的且无经典对应的量子系统,对二态系统的同构表示的认识和研究能启发研究人员对其动力学与统计行为的更深刻理解.本文使用在[J.Chem.Phys.145,204105(2016);J.Chem.Phys.151,024105(2019);J.Phys.Chem.Lett.12,2496(2021)]等文章中发展的约束相空间严格理论、非协变相空间函数、含时权重函数与含时归一化因子来构建一类新型量子相空间表示.这类同构表示可以导出二态量子系统布居动力学的准确结果.约束相空间上的轨迹运动方程同构于含时薛定谔方程.每条相空间轨迹对于布居动力学所对应积分表达式的贡献严格半正定。进一步证明了在[J.Chem.Phys.145,144108(2016)]这篇文章中根据经验提出的三角窗函数方法在本质上可以对应于本文的这类新型相空间表示的一个特殊情况,因此同样是二态量子系统准确布居动力学的同构表示.

基于双通道回声状态网络的时间序列补全及单步预测

随着物联网的发展,众多传感器采集到大量具有丰富数据相关性的时间序列,为各种数据挖掘应用提供强大的数据支持。然而,一些客观或主观原因(如设备故障、稀疏感知等)往往会造成采集到的数据出现不同程度的缺失。虽然已有很多方法被提出用于解决这一问题,但这些方法在数据相关性方面或考虑不够全面,或计算成本过高。而且,现有方法仅关注对缺失值的补全,未能兼顾下游应用。针对上述不足,设计了一种兼顾补全与预测任务的双通道回声状态网络。两个通道的网络虽共用输入层,但具有各自的储备池和输出层。两者最大的区别是左/右通道的输出层分别表示输入层前/后一个时刻对应的目标值或预补值。最后将两个通道的估计值进行融合,充分利用来自缺失时刻之前和之后的数据相关性以进一步提升性能。两种缺失现象下(随机缺失和分段缺失)不同缺失率的实验结果表明,所提模型无论是在补全精度还是预测精度上都优于目前流行的各类方法。

相敏操控对制备低频双模正交压缩真空态光场的影响

本文提出了利用单边带移频光实现非简并光学参量放大器相敏操控的方案,实验研究了在对非简并光学参量放大器相敏操控过程中,单边带移频光注入的方案和信号光注入的方案对产生的低频双模正交压缩真空态光场的影响.实验结果表明,信号光注入非简并光学参量放大器实现相敏操控过程中,压缩真空态的压缩度随着注入信号光场功率的增加不断减小直至消失.而在单边带移频光注入非简并光学参量放大器实现相敏操控过程中,正交振幅和正交位相压缩真空态的压缩度对注入移频光场的功率变化都不敏感,压缩度几乎不变.采用单边带移频光方案实现稳定的相敏操控,非简并光学参量放大器运转于相敏放大状态达30 min,获得了稳定输出的低频双模正交压缩真空态光场,在傅里叶分析频率为200 kHz测量的正交振幅分量的压缩度为(4.1±0.1)dB,正交位相分量的压缩度为(4.0±0.2)dB.

两态模型中的振动态布居转移

以氢化锂极性双原子分子为例,运用含时量子波包法数值求解两态模型,从理论方面研究了基电子态X^(1)Σ^(+)通过跃迁偶极矩到激发电子态A^(1)Σ^(+),两态模型中的振动态布居转移过程.基电子态上以及激发电子态上各自的振动态通过激光脉冲与永久偶极矩作用完成布居转移过程也考虑在内.在紫外光和红外光区域内,使用短的线性偏振激光脉冲实现了高效的布居转移.经过选择激光脉冲的峰值强度、中心频率以及持续时间等参数,在激光脉冲关闭后,最终的布居转移几率都超过了90%.

任意未知三维二粒子态的短距离量子隐形传态

为克服长距离量子隐形传态方案中局域操作受限,且易受环境干扰影响通信质量的缺陷,利用1个三维Bell态和1个处于基态的辅助粒子作为量子信道,提出一个任意未知三维二粒子态的短距离量子隐形传态新方案.在该方案中,发送方和接收方除共享三维Bell态外,还必须预先共享1个辅助粒子.发送者对辅助粒子执行量子门运算后,需对其Bell粒子和未知量子系统进行联合测量,并向接收者发送该测量的经典信息.结果表明,接收者以100%的概率将自己拥有的Bell粒子与辅助粒子的量子态转换成被发送者摧毁的未知量子态的精确复制品.本方案传输距离短、承载信息量大、耗费纠缠资源少,在诸如芯片的固态器件上的量子隐形传态有很好的应用前景.

天然气储层裂隙中气-液两相流的流态转变条件数学模型

气-液两相在储层裂隙中流动时可能存在气泡流、段塞流、环雾流等流态,查明流动时流态转变条件能为气-液两相流流态形成机理研究提供依据,有助于天然气井的生产管控。根据气-液两相流不同流态的流动特点,结合连续介质控制理论和动量守恒原理,构建了气泡流-段塞流-环雾状流等流态之间转变的数学模型,确定了各流态间变化的临界条件和主控因素,通过气-液运移产出微观流动物理模拟试验验证了所建数学模型的准确性。结果表明:气-液两相在裂隙中的流态转变是气/液相的物理性质、注气通道孔径、裂隙流动通道孔径、气相流体流速、液相流体流速等因素耦合作用的结果。气泡流与段塞流能否转变主要取决于初生气泡大小、流动通道空间、液相界面波高度;段塞流与环雾流间能否转变取决于气相流体能否击碎液相流体并使之悬浮。不同流态间转变的主要控制因素不同:气泡流与段塞流相互转变的主控因素为裂隙系统的孔径,注气通道孔径越大、流动通道孔径越小,越容易发生段塞流;段塞流与环雾流相互转化的主控制因素为流体流速、气/液相流体的物理性质,气/液相对速度越大、气/液密度差越小、液相表面张力越小,越容易发生环雾流。研究成果能够为天然气储层裂隙中气-液两相流态形成机理和天然气运移产出研究提供理论依据。

美国两党对华政策的基本共识与关键分歧

自2018年美国对华政策转向强硬以来,特朗普政府与拜登政府都主张对华战略竞争。这表明美国两党的对华政策达成基本共识,将中国作为“主要挑战与对手”,逐渐偏离过去的对华“接触政策”,转而采取以竞争为主的对华政策。尽管美国两党的对华政策在转向强硬方面具有共识,都以战略竞争概括其对华政策,但在对华强硬程度上存在分歧,且两党在对华战略定位、政策目标、竞争强度与合作意愿方面也不尽相同。美国两党对华政策的关键分歧,就是民主党试图坚持对华战略竞争,同时确保中美竞争不失控;共和党则倾向于对华更激烈的竞争,对华政策具有较强的对抗色彩。美国两党对华政策出现分歧,既有两党背后的利益群体与价值观存在差异的深层原因,也有两党政策精英的对华交往水平存在差异的因素。未来,美国两党对华政策的分歧将继续存在,也有趋同演进的可能。中国需积极应对,加强与美国保守派的政策交流,尽快确立发展中美关系的指导原则,尽力牵制共和党对华战略中的消极倾向,推动中美关系朝着健康、稳定的方向发展。