双光子共振介质光学双稳特性的理论研究

本文给出了有关双光子共振介质中光学双稳的一般理论。分析了在双光子离共振和双光子近共振情形下的光学双稳特性,以及在双光子近共振情形时的瞬态光学双稳特性。在分析过程中建立和运用了双光子矢量模型。在数值计算的基础上作出了钠蒸汽中双光子共振附近情形下的光学双稳特性曲线。 关键词：     

多光子光学双稳性的研究

本文给出了描述多光子光学双稳性和多光子激光的统一量子力学模型,得到了多光子光学双稳性和多光子激光的态方程,给出了计算多光子光学双稳住阈值的方法.对势函数进行分析之后,得到了静态稳定性判据和开关特性的物理解释,划分了多光子光学双稳特性曲线上的稳定区域和亚稳定区域,指出多光子光学双稳态实际上是多光于光学稳-亚稳双态.本文还讨论了多光子光学双稳态和多光子激光器中的相变问题.     

国外光学与光电子学的新进展(Ⅸ)——光学双稳性

<正> 严格地说,如果一个系统在某一输入值区间中的同一输入光强值上有两个稳态输出光强,那么就称该系统呈光学双稳性。八十年代以来对光学双稳性有了更宽的解释,它包含了某些工作条件下呈现双稳性的非线性光学系统的全部稳态和暂态特性。光学双稳性的专题会议和该题材的教科书都涉及到双稳态系统物理学的许多方面,包括非稳性(在恒定输入下的暂态现象)和光学开关(以光控制光)。     

PM晶体声光混合型光学双稳态原理设计及频率反馈网络系统研究

本文简介PbMoO₃混合型光学双稳态的原理设计及其反馈网络系统的装置。通过实验及调节,测试了该器件的衍射曲线,反馈曲线以及光学双稳滞后回线。实践证明:PbMoO₃声光晶体具有良好的光学双稳特性,可以作为多通道开关,适用于波导技术。     

酞菁铜LB薄膜复合光波导的高速双稳特性

对以有机材料酞菁铜的LB薄膜作覆盖层的K~+离子交换玻璃光波导,进行了高速光学双稳特性研究.利用比较波导的输入和输出光脉冲形状法,在532nm光波长得到开关时间为24ps的高速光学双稳特性.     

光学双稳性的尖顶突变模型

本文提出一个描述光学双稳性的简明的突变理论模型,由此得到产生光学双稳性的阈值条件,并指出控制双稳特性的方法.     

颗粒复合介质在高温下的光学双稳特性

利用Maxwell-Garnett近似，结合谱表示方法，理论研究了金属/绝缘颗粒复合介质的光学双稳特性随环境温度的依赖关系.数值结果表明，体系的光学双稳区域随环境温度的升高而逐渐变窄，甚至消失.还进一步研究了复合体系的折射系数和消光系数随温度的变化关系. 关键词： 颗粒复合介质 光学双稳     

利用带模型探讨染料环形腔系统的光学双稳特性

利用染料分子带模型，探讨了染料环形腔系统的光学双稳特性，得到光学双稳可在一个比较大的频率范围内实现；其双稳区域是染料分子带结构参数（带宽及偶极分布的Ｌｏｒｅｎｔｚｉａｎ宽度等）的函数． 关键词：     

PM晶体声光混合型光学双稳态原理设计及频率反馈网络系统研究

本文简介PbMoO_3混合型光学双稳态的原理设计及其反馈网络系统的装置。通过实验及调节,测试了该器件的衍射曲线,反馈曲线以及光学双稳滞后回线。实践证明:PbMoO_3声光晶体具有良好的光学双稳特性,可以作为多通道开关,适用于波导技术。     

不同声场状态下的声光光学双稳态

本文分析了具有不同行波系数α的声光光学双稳特性,研究了声场状态对双稳特性的影响,进而指出,仅当声场具有一定的α值时,声光光学双稳态才有实际用途,如果α=1,即纯驻波情况下声光双稳性则失去了意义。实验与理论相符。     

Thermodynamics and phase transitions in dissipative and active Morse chains

We study the evolution of a simple one-dimensional chain of N=4 particles with Morse interactions and periodic boundary conditions which are imbedded into a heat bath creating dissipation and noise. The investigation is concentrated on thermodynamic properties for equilibrium, near-equilibrium and far-equilibrium conditions. For the thermodynamic equilibrium, created by white noise and passive friction obeying Einsteins fluctuation dissipation relation, we find a standard phase diagram. By applying active friction forces the system is driven to stationary non-equilibrium states, creating conditions where various self-sustained oscillations are excited. Thermodynamic quantities like energy, pressure and entropy are calculated near equilibrium, around a critical distance from equilibrium and far from equilibrium. We observe maximal order (minimum entropy) in certain region of the noise temperature, a phenomenon which is reminiscent of stochastic resonance. With increasing distance from equilibrium new phases corresponding to the existence of several attractors of the dynamical stem appear.     

A generalization of the relativistic equilibrium equations for a non-rotating star

The problem of elastomechanical equilibrium for a static, spherically symmetric star composed of an elastic material is analyzed. A suitable formulation of relativistic elasticity theory is used, and the second order equilibrium equations are found. It is shown that the equilibrium conditions with anisotropic pressure introducedad hoc by some authors are in fact the dynamical conditions for a relativistic elastic material. The corresponding first order equations for the components of the metric and of the energy-momentum tensor reduce to the Tolman-Oppenheimer-Volkhoff equations if the material exhibits no shape-rigidity. Two interesting classes of solutions are discussed.     

On the meaning of the canonical ensemble

Thermal equilibrium between (quantum) systems is taken to mean stability for the combined system. Necessary and sufficient conditions for such stability are found and used to show that any system in equilibrium with suitably complex second system (heat bath) will be characterized by a canonical ensemble. Thus the notion of temperature is derived directly from that of equilibrium, without, for example, recourse to microcanonical ensembles or information theory. Discussed briefly are the generalization of these results to grand canonical ensembles and their application to the equilibrium between a black hole and the surrounding radiation field.     

Stochastic evolutionary public goods game with first and second order costly punishments in finite populations

We study the stochastic evolutionary public goods game with punishment in a finite size population. Two kinds of costly punishments are considered, i.e., first-order punishment in which only the defectors are punished, and second-order punishment in which both the defectors and the cooperators who do not punish the defective behaviors are punished. We focus on the stochastic stable equilibrium of the system. In the population, the evolutionary process of strategies is described as a finite state Markov process. The evolutionary equilibrium of the system and its stochastic stability are analyzed by the limit distribution of the Markov process. By numerical experiments, our findings are as follows.(i) The first-order costly punishment can change the evolutionary dynamics and equilibrium of the public goods game, and it can promote cooperation only when both the intensity of punishment and the return on investment parameters are large enough.(ii)Under the first-order punishment, the further imposition of the second-order punishment cannot change the evolutionary dynamics of the system dramatically, but can only change the probability of the system to select the equilibrium points in the "C+P" states, which refer to the co-existence states of cooperation and punishment. The second-order punishment has limited roles in promoting cooperation, except for some critical combinations of parameters.(iii) When the system chooses"C+P" states with probability one, the increase of the punishment probability under second-order punishment will further increase the proportion of the "P" strategy in the "C+P" states.     

Preparation and relaxation of very stable glassy states of a simulated liquid

We prepare metastable glassy states in a model glass former made of Lennard-Jones particles by sampling biased ensembles of trajectories with low dynamical activity. These trajectories form an inactive dynamical phase whose "fast" vibrational degrees of freedom are maintained at thermal equilibrium by contact with a heat bath, while the "slow" structural degrees of freedom are located in deep valleys of the energy landscape. We examine the relaxation to equilibrium and the vibrational properties of these metastable states. The glassy states we prepare by our trajectory sampling method are very stable to thermal fluctuations and also more mechanically rigid than low-temperature equilibrated configurations.     

Dynamics of money

We present a dynamical many-body theory of money in which the value of money is a time dependent "strategic variable" that is chosen by the individual agents. The value of money in equilibrium is not fixed by the equations, and thus represents a continuous symmetry. The dynamics breaks this continuous symmetry by fixating the value of money at a level which depends on initial conditions. The fluctuations around the equilibrium, for instance in the presence of noise, are governed by the "Goldstone modes" associated with the broken symmetry. The idea is illustrated by a simple network model of monopolistic vendors and buyers.     

分析力学中加速度的去魅

利用经典力学的拉格朗日方法,分别讨论了静平衡的条件和连续介质动力学.利用哈密顿方法,介绍了相空间中独特的平衡点以及适用于统计力学的稳定系综分布.这些例子表明:在分析力学的框架内,加速度概念已经去魅,所谓的“平衡态”也具有不同于牛顿方法的实现方式.     

Order and disorder in the approach to equilibrium of a classical gas

We study the approach to equilibrium of a classical gas. The initial condition corresponds to a Maxwell velocity distribution, but to a nonequilibrium binary correlation. We consider two cases. In the first, there are initially no spatial correlations, while in the second, initial correlations correspond to long-range spatial order. We show that the gas leaves the Maxwell velocity distribution function in the process of building up equilibrium correlations. The spatial correlations in the equilibrium state are seen to emerge from a self-organization process in the gas. Non-Markovian effects play an essential role in this process by coupling the velocity distribution and the binary correlations. For the case of initial long-range correlations we obtain anti-Boltzmann behavior in the evolution of the velocity distribution as the Boltzmann entropy decreases from the nonequilibrium to the equilibrium state. For this case we also have nontrivial behavior on a short time scale due to the non-Markovian effects. The approach used here is based on the theory of subdynamics as developed in previous publications. The results obtained show the interplay between irreversible processes leading to disorder and to order in a classical gas.     

Effects of random-crystal-field on the kinetic Blume Capel model

The effects of random crystal field on the stationary states of the kinetic spin-1 Blume Capel model are studied using the Glauber-type stochastic dynamics under the time-dependent oscillating field assumption. Our investigation, based on the equilibrium ground state phase diagram, revealed many interesting phenomena. The known phases, in the equilibrium case, are obtained for high field and are represented by limit cycles. The phase diagram of the pure pure kinetic Ising spin- and spin-1 Blume Capel models are deduced as particular cases. First-order, second-order transition lines, dynamical critical and dynamical double critical end points are also obtained.     

Influence of radiation resorption on criteria of the existence of local thermodynamic equilibrium

The emission of radiation from a plasma volume upsets the Boltzmann equilibrium. A number of authors have proposed criteria for approximate testing of the existence of local thermodynamic equilibrium on the basis of collision and radiation processes. However, those criteria give excessive values, because they do not take into account radiation resorption, which can moderate the test conditions. The present article is concerned with the influence of radiation resorption on the criterion of the existence of local thermodynamic equilibrium in a low-temperature plasma. The domain of existence of local thermodynamic equilibrium (in the sense of Saha-Boltzmann equilibrium) is calculated for electric arcs.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 20–24, June 1986.