Nonadiabatic geometric phase in a doubly driven two-level system

We study theoretically the nonadiabatic geometric phase of a doubly driven two-level system with an additional relative phase between the two driving modes introduced in. It is shown that the time evolution of the system strongly depends on this relative phase. The condition for the system returning to its initial state after a single period is given by the means of the Landau–Zener–Stückelberg–Majorana destructive interference. The nonadiabatic geometric phase accompanying a cyclic evolution is shown to be related to the Stokes phase as well as this relative phase. By controlling the relative phase, the geometric phase can characterize two distinct phases in the adiabatic limit.

Weak-Coupling Theory for Semiclassical Periodically Driven Two-Level Systems： Beyond Rotating-Wave Approximation

We present a weak-coupling theory of semiclassical periodically driven two-level systems. The explicit analytical approximating solution is shown to reproduce highly accurately the exact results well beyond the regime of the rotating-wave approximation.

Quantum Computation with Two-Level Systems in Current-Biased Josephson Junction

We present a feasible scheme that realizes quantum computation using the two-level systems （TLSs） in Current-biased Josephson junction （CBJJ） under the present experimental technology. Effective manipulation of the TLSs by CBJJ serving as register qubit can be obtained, such as initialization, single-qubit rotations, two-qubit gates, entanglement generation, and read out, etc. In addition, we also discuss the experimental feasibility and efficiency of the scheme.

Weak-Coupling Theory for Low-Frequency Periodically Driven Two-Level Systems

We generalize the Wu-Yang strong-coupling theory to solve analytically periodically driven two-level systems in the weak-coupling and low-frequency regimes for single- and multi-period periodic driving of continuous-wave-type and pulse-type including ultrashort pulses of a few cycles.We also derive a general formula of the AC Stark shift suitable for such diverse situations.

Multiple induced transparency in a hybrid driven cavity optomechanical device with a two-level system

We present a scheme with the multiple-induced transparency windows in a hybrid optomechanical device.By studying the transmission of a probe field through the hybrid device,we show the successive generations of three transparent windows induced by multiple factors including tunneling,optomechanical and qubit-phonon coupling interactions,and analyze the physical mechanism of the induced transparency based on a simplified energy-level diagram of the system.Moreover,the effects of the transition frequency and decay rate of the two-level system on the multiple-induced transparency windows are discussed.We find that the transparency windows can be modulated by the coupling interaction between the qubit and NMR,the decay of qubit and the power of the control field.Therefore,the transmission of the probe field can be coherently adjusted in the hybrid cavity optomechanical device with a two-level system.

Analytical Solution of Weak-Coupling Periodically Driven Two-Level System

We present an approximate analytical solution to periodically driven two-level system in the weak-coupling regime. The analytical solution is in good agreement with the exact numerical solution in resonance and near resonance cases when Ω 〈 0.3ωa with Ω and ωa denoting the Rabi and transition frequencies respectively.

Renormalization: single-photon processes of two-level system in free space

The investigation on quantum radar requires accurate computation of the state vectors of the single-photon processes of the two-level system in free space. However, the traditional Weisskopf-Wigner(W-W) theory fails to deal with those processes other than spontaneous emission. To solve this problem, we provide a new method based on the renormalization theory. We evaluate the renormalized time-ordered Green functions associated with the single-photon processes, and relate them to the corresponding state vectors. It is found that the ultraviolet divergences generated by the Lamb shift and higher-order interactions can be systematically subtracted in the state vectors. The discussions on spontaneous emission and single-photon absorption are then presented to illustrate the proposed method. For spontaneous emission, we obtain the same results of the W-W theory. For single-photon absorption where W-W theory fails, we find that the two-level electric dipole first gets excited rapidly and then decays exponentially, and that the efficiency of the single-photon absorption declines as the bandwidth of the incident photon becomes narrow. The proposed method can improve the investigation on quantum radar.

Dynamical Evolution of an Effective Two-Level System with PT Symmetry

We investigate the dynamics of parity-and time-reversal（PT） symmetric two-energy-level atoms in the presence of two optical and one radio-frequency fields. The strength and relative phase of fields can drive the system from the unbroken to the broken PT symmetric regions. Compared with the Hermitian model, Rabi-type oscillation is still observed, and the oscillation characteristics are also adjusted by the strength and relative phase in the region of the unbroken symmetry. At the exception point, the oscillation breaks down. To better understand the underlying properties we study the effective Bloch dynamics and find that the emergence of the PT components of the fixed points is the feature of the PT symmetry breaking and the projections in the x–y plane can be controlled with high flexibility compared with the standard two-level system with the PT symmetry. It helps to study the dynamic behavior of the complex PT symmetric model.

Features of Excitation of a Two-Level System by Short Nonresonance Laser Pulses

This paper is devoted to theoretical investigation of characteristic features arising during excitation by short nonresonance laser pulses. The treatment is made within the applicability of perturbation is given to the dependence of total excitation probability from eigenfrequency of TLS. Various laser pulse shapes of TLS on the pulse duration for different detuning are considered. two-level system （TLS） approach. Main attention of carrier laser frequency

Steady-state relation of a two-level system strongly coupled to a many-body quantum chaotic environment

We study the long-time average of the reduced density matrix(RDM)of a two-level system as the central system,which is locally coupled to a many-body quantum chaotic system as the environment,under an overall Schr?dinger evolution.A phenomenological relation among elements of the RDM is proposed for a dissipative interaction in the strong coupling regime and is tested numerically with the environment as a defect Ising chain,as well as a mixed-field Ising chain.

连续时间门限完全服务两级轮询系统性能分析

为区分业务优先级以及提高系统公平性与稳定性,在简化求解过程的基础上,提出一种连续时间门限完全服务两级轮询系统。系统状态由马尔科夫链得出并根据其建立数学模型,系统的平均循环周期、平均排队队长等性能参数由对数学模型的概率母函数进行求导所得,将求导结果与仿真实验进行对比,验证理论分析的准确性。将该系统与单级系统、其它两级系统进行对比,验证了该系统在保证业务优先级的同时更具公平性与稳定性。

永磁同步风力发电系统的最大功率跟踪模糊分数阶控制

在“双碳”背景下,风电作为零碳电力和新能源发电的主力军,在助力社会全面绿色低碳转型方面发挥了关键性作用。在保证发电稳定的前提下实现风能的最大化利用,提升风力发电系统发电量至为重要。文中针对永磁同一步风力发电系统的最大功率跟踪(maximum power point tracking, MPPT)问题进行研究。首先建立了永磁同步风力发电系统的机理仿真模型,用两电平双PWM全功率换流器连接风力发电机与电网。然后基于以上模型,分别设计了整数阶PI控制器、分数阶PI"控制器、模糊分数阶PP控制器以实现MPPT控制。最后对以上控制策略进行了仿真研究。结果表明,无论在阶跃风速还是随机风速下,模糊分数阶PU控制器相较于其他两种均具有更出色的MPPT性能与更强的鲁棒性。

一类复杂工业过程的数据驱动与PID协调控制

针对一类具有强非线性且难以建立精确数学模型的复杂工业过程,提出了一种基于PID与数据驱动的协调控制策略。在系统初始阶段,采用PID控制方法,不需要建立系统的数学模型,就能获得大量系统输入输出(I/O)数据。在系统稳态阶段,提出了多输入多输出(multiple input multiple output,MIMO)无模型自适应离散终端滑模控制(model-free adaptive discrete terminal sliding mode control,MFA-DTSMC)方法,该方法基于系统的紧格式动态线性化数据模型,且伪Jacobian矩阵(pseudo-Jacobian matrix,PJM)估计算法仅取决于被控对象的I/O测量数据。其次,设计了一种协调控制策略,实现了PID与数据驱动控制器之间的协调控制。以双容水箱液位系统为例进行仿真实验,仿真结果验证了所提控制策略的有效性。

Chiral bound states in a staggered array of coupled resonators

We study the chiral bound states in a coupled-resonator array with staggered hopping strengths,which interacts with a two-level small atom through a single coupling point or two adjacent ones.In addition to the two typical bound states found above and below the energy bands,this system presents an extraordinary chiral bound state located within the energy gap.We use the chirality to quantify the breaking of the mirror symmetry.We find that the chirality value undergoes continuous changes by tuning the coupling strengths.The preferred direction of the chirality is controlled not only by the competition between the intracell and the intercell hoppings in the coupled-resonator array,but also by the coherence between the two coupling points.In the case with one coupling point,the chirality values varies monotonously with difference between the intracell hopping and the intercell hoppings.While in the case with two coupling points,due to the coherence between the two coupling points the perfect chiral states can be obtained.

基于扰动观测器的双容液位系统RBF神经网络滑模控制

针对双容液位系统存在的外部扰动、模型参数不确定等问题,设计了一种基于非线性扰动观测器(nonlinear disturbance observer,NDOB)的径向基函数神经网络滑模控制(radial basis function neural network sliding mode control,RNNSMC)方法。建立双容液位系统数学模型,采用积分型滑模面来提高系统的鲁棒性,在常规积分滑模控制的基础上,通过RBF神经网络(RBF neural network,RNN)对系统的非线性函数进行逼近,并设计非线性扰动观测器估计外部扰动,选用Lyapunov稳定性判据证明了控制策略的闭环稳定性。仿真结果表明,所提控制策略与积分滑模控制(integral sliding mode control,ISMC)方法相比,不需要精确的数学模型,且控制精度更高,抗干扰能力更强。

基于系统论的高等学校两级教学管理改革

论述了高等学校实行两级教学管理的重要性,分析了两级教学管理改革现状。基于系统论,以教学管理系统特征为切入点,探讨了系统基本原理、规律及方法在高等学校两级教学管理体制机制建设中的指导意义,从理论和实践双重层面构建了“七位一体”校院两级系统化教学管理模式。认为该模式突出强调人的主体价值,能够有效提升教学管理效能,促进学校治理体系与治理能力现代化。

Exact analytical results for a two-level quantum system under a Lorentzian-shaped pulse field

We investigate a two-level quantum system driven by a Lorentzian-shaped pulse field.An analytical solution is presented in terms of the confluent Heun functions.It is shown that for specially chosen parameter conditions,there are a number of the exact analytical solutions in an explicit form.The dependence of the final transition probabilities in the two levels on the system parameters is derived analytically and confirmed numerically.

Optical bistability and multistability via amplitude and phase control in a Duplicated two-level system

We investigate the optical bistabiiity （OB） in a duplicated two-level system contained in a ring cavity. The atoms are driven by two orthogonally polarized fields with a relative phase. The OB behavior of such a system can be controlled by the amplitude and the relative phase of the coupling field, and it is possible to switch between bistabilitv and multistability by adjusting the relative phase.

国网供应链运营中心两级数据管理体系构建及应用

通过梳理国网供应链运营中心数据管理及其运作的相关工作现状及存在问题,结合两级供应链运营中心运作及其数据管理体系在数据贯通及协同、取数逻辑与业务应用、底表关联与应用开发、数据管理及联动机制以及供应链数据质量管理等方面存在的挑战,提出了国网供应链运营中心数据管理的新思路、新模式、新技术和新场景,系统构建了国网供应链两级数据管理体系,具体涉及生成供应链统一业务数据资产目录、搭建国网两级数据管理及协同治理机制、设计供应链业务数据标准及其模型和开展供应链全过程数据可视化管理,并结合浙江电力“两金一款”业务场景进行了数据管理应用,以期为国网供应链运营中心两级数据管理体系构建提供理论依据及其管理实践提供创新方向。

新型电力系统下省间-省内2级市场交易模式设计及出清优化

为实现“碳达峰,碳中和”目标,习近平总书记提出构建以新能源为主体的电力系统。建立面向低碳能源转型的新型电力系统市场交易模式是实现“双碳”目标的重要途径之一。为此,提出省间-省内2级市场交易模式及出清优化模型。首先,分析新型电力系统下高比例清洁能源接入、高比例跨区电力输送以及高比例灵活资源调节的特征并描述其市场交易框架。其次,设计以新能源为主体的省内市场交易,包括年度双边协商/集中竞价交易、月度双边协商/集中竞价交易、月内(多日)交易以及辅助服务交易;设计省间交易模式,包括年度/月度跨省跨区交易、省间购电交易、清洁能源外送交易以及省间调峰辅助服务交易。在满足电力供需平衡的基础上,构建以省内清洁能源消纳量最大为目标的日前市场出清模型和以总成本最小为目标的日内市场出清模型。最后,以某省新型电力系统为例,模拟典型场景下的日前市场交易和日内市场交易,结果表明所提市场交易模式有效地促进了清洁能源消纳,减缓了弃风弃光、拉闸限电等现象的发生,推动了“双碳”目标的实现。