Revival Time Estimation in the Process of Down Conversion

Abstract

We analyse the collapse-revival phenomenon in the process of k-photon down conversion with quantized pump for initial Fock states. We give an explanation for the appearance of the revivals by analysing the decomposition of the initial state into the interaction Hamiltonian eigenvectors. A quantitative estimation of the revival times is given as well.     

Effects of Dipole Interaction on the Collapse-revival Phenomenon of Rabi Oscillations

Abstract

The sensitivity of the collapse-revival phenomenon of Rabi oscillations of two identical atoms to dipole-dipole interaction is brought out by deriving the analytical expression of the excitation probability of two interacting atoms in a coherent field. We study this effect in a two-photon model in which the time evolution is exactly periodic.     

Quantum Superpositions of Binomial States of Light

We introduce new kinds of states of electromagnetic field, which are quantum superpositions of binomial states. They not only exhibit remarkable non-classical properties but can also interpolate between the ‘Schrödinger cat’ type of states and the number states in a particularly interesting way. We basically discuss some of their main statistical properties, as well as schemes for their generation. We also employ quasiprobability distributions in phase space.     

Collapse-revival Phenomenon in the Jaynes-Cummings Model Interacting with the Multiphoton Holstein-Primakoff SU(2) Coherent State

Abstract

We have analysed the behaviour of the atomic population inversion of the two-level atom interacting with a single-mode field initially prepared in the multiphoton Holstein-Primakoff SU(2) coherent state. It is shown that the behaviour of the atomic inversion depends on the parameters characterizing the initial state of the field. In particular, the atomic inversion can exhibit periodical oscillations as well as the collapse-revival phenomenon.     

Squeezing in Finite Superpositions of Photon-number States without the Vacuum

Abstract

We show that a finite superposition of photon-number states without the vacuum state can lead to squeezed fluctuations. The properties of these states are discussed.     

Interaction of Superpositions of Coherent States of Light with Two-level Atoms

Abstract

We investigate some of the basic features of the interaction of superpositions of coherent states of light with two-level atoms in the framework of the Jaynes-Cummings model. We compare the behaviour of the system in the case of having a coherent superposition state and a statistical mixture of coherent states as an initial field. We investigate the collapses and revivals of the atomic inversion by studying the evolution of the Q function of the cavity field. We also establish the connection between the purity of the field and the collapses and revivals of the atomic inversion.     

On the Interaction of Two-level Atoms with Superpositions of Coherent States of Light

Abstract

In this paper we study the decoherence process occurring when a field prepared in quantum superpositions of coherent states (Schrödinger cats) interacts with a two-level atom in the framework of the Jaynes-Cummings model. We emphasize the influence of the relative phase in the initial superposition state on the purity of the field during the evolution     

Generation and Properties of Superpositions of Displaced Fock States

Abstract

We study the statistical properties of superpositions of displaced Fock states. We find that for the superposition of the form ¦ψ₁〉 = 1/√2(¦α, n〉 + ¦α, k〉) the direction of the displacement (α positive or negative) plays an important role; also, if n = 1 and k = 0 a strong sub-Poissonian character is found for α ≥ 0. We also analyse the ways in which superpositions of displaced Fock states may be generated.     

Photon Statistics of an m-photon Laser with k-photon Losses

With the help of an approximation scheme valid for n ? 1 and Δ ⁿ² ?n ^-2 (where n is the mean value and Δ ⁿ² the variance of the photon number), the photon statistics of an m-photon laser with k-photon losses (m,k = 1, 2, …) is studied theoretically for arbitrary values of the atomic population inversion s produced by an external pumping source. For m>k, m = k and m < k, the dependences of the steady-state values of the mean photon number and of the quantity Δ ⁿ² / n on gain and saturation are investigated. In the limit of strong saturation (well above the threshold for m > k) the photon statistics are characterized by the steady-state value Δ ⁿ² / n = (1/2) (1 + m/ks).     

Nonlinear Dissipative Oscillator with Displaced Number States

Abstract

We study the interaction of a Kerr-like medium with light initially prepared in a displaced number state. We analyse squeezing properties and photon statistics at the output of a Kerr-like medium. We show that under certain conditions the superposition of two displaced number states can be created. We study the influence of dissipation on the formation of the superposition state.     

Study of Induced Temporal Coherence in Optical Parametric Down Conversion

Abstract

Temporal coherence of the idler photon beam induced by a coherent input signal was studied for non-degenerate optical parametric down conversion. When the optical path difference of the interferometer is much longer than the coherence length of the spontaneous idler radiation, the experimental results show that the first-order temporal coherence of the idler photon can be induced by a coherence input signal and the interference fringe visibility is determined by the intensity of the coherent input signal.     

Phase Properties of Squeezed Number States

Abstract

We have studied the phase properties of the squeezed number states by evaluating the expression for the phase probability distribution and the phase variance. In addition, the expression for the photon number distribution of the squeezed phase states has been evaluated.     

Absolute Calibration of Analog Detectors by Using Parametric Down Conversion

This paper reports a systematic study of a promising absolute-calibration technique of analog photodetectors based on the properties of parametric down conversion. Formal results and a preliminary uncertainty analysis show that the proposed method can be effectively developed with interesting applications to metrology     

粉石英细磨过程中的团聚现象

以粉石英为例，揭示了超细粉碎过程中特有的团聚现象．以大量实验数据和理论分析为基础，描述和论证了团聚现象的种种表现．具有普遍的意义。为在超细粉碎中合理选择工艺条件．有效控制粉碎极限和延缓粉碎平衡，推迟“逆粉碎”的出现提供了一定的参考依据，对推进粉体技术的发展具有一定的理论意义和实用价值。     

基于载流子数目变化的EAM模型实现波长变换

对比SOA的交叉增益效应,基于EAM的交叉吸收效应实现波长变换具有结构简单、转换效率高等优点.文中分析了MQW-EAM交叉吸收效应实现波长变换的原理,设计了实现波长变换的实验装置, 并对现有的EAM的交叉吸收效应模型进行了改进,使其可用于多光束信号注入情况.并分两种情况对EAM数学模型进行了详细分析,根据模型仿真得出了单高斯脉冲注入和强信号注入下的载流子浓度关系图,仿真结果与事实原理吻合较好.     

铝合金表面无铬导电转化膜的制备工艺

铬酸盐转化工艺严重污染环境,应用受限,新开发的常用转化技术的耐蚀、导电性不及铬酸盐,而且也未投入工业应用.以钼酸盐为主要成膜氧化剂,在溶液中添加氟化钠等成分,利用浸溃法在铝合金表面制备出了金黄色的钼酸盐导电转化膜.采用点滴法评价了转化膜的耐蚀性,借助四点测电阻法测试了膜层的导电性能,导电转化膜表面电阻约为3 mΩ·cm.通过化学导电转化膜形成过程的电位-时间曲线,探讨了化学成膜机理.结果表明:钼酸铵、氟化钠含量,溶液pH值、温度、处理时间等对转化膜的外观、性能影响明显.本工艺所制备的转化膜其耐蚀性、导电性基本符合工业应用要术.     

Measurement of the Efficiency of Detection by Single-Photon Counters Based on Avalanche Photodiodes by the Method of Spontaneous Parametric Down Conversion with Spectrally Asymmetric Channels

Measurement Techniques - We consider a frequency-diaphragm technique of simultaneous standardless measurements of the efficiency of photon detection by two single-photon counters. This technique is...     

Evaluation of the Error of the Method of Superpositions of One-Dimensional Solutions in Nonstationary Heat-Conduction Problems

Examples of the use of the approximate method in solution of nonstationary heat-conduction problems are given. The error of this method is evaluated by comparison with exact solutions; it turns out to be several orders of magnitude smaller than the error in finite-difference methods. Recommendations on employment of the method are given on the basis of the numerical experiments conducted.     

Modeling of the Nonstationary Process of Conversion of Methane to Hydrogen in a Filtration-Combustion Wave

Experimental data on incomplete oxidation of methane in air are analyzed for the stoichiometric relation = 4 using a numerical model; the data are obtained with different charges and for different flow rates of feed of a mixture. In order to explain the experimental data, it is proposed that a heterogeneous reaction that ensures the beginning of the processes of oxidation of methane at lower temperatures be introduced into the chemical model.