Wigner functions and tomograms of the photon-depleted even and odd coherent states

Using the coherent state representation of Wigner operator and the technique of integration within an ordered product （IWOP） of operators, this paper derives the Wigner functions for the photon-depleted even and odd coherent states （PDEOCSs）. Moreover, in terms of the Wigner functions with respect to the complex parameter a the nonclassical properties of the PDEOCSs are discussed. The results show that the nonclassicality for the state ｜β, m〉o （or ｜β,m〉e） is more pronounced when m is even （or odd）. According to the marginal distributions of the Wigner functions, the physical meaning of the Wigner functions is given. Further, the tomograms of the PDEOCSs are calculated with the aid of newly introduced intermediate coordinate-momentum representation in quantum optics.

Even and Odd Coherent States for Time-Dependent Harmonic Oscillator

The dynamical invariant for a general time-dependent harmonic oscillator is constructed by making use of two linearly independent solutions to the classical equation of motion. In terms of this dynamical invariant we define the time-dependent creation and annihilation operators and relevantly introduce even and odd coherent states for time dependent harmonic oscillator. The mathematical and quantum statistical properties of these states are discussed in detail. The harmonic oscillator with periodically varying frequency is treated as a demonstration of our general approach.

Continuous-variable quantum teleportation of even and odd coherent states through varied gain channels

This paper has investigated quantum teleportation of even and odd coherent states in terms of the EPR entanglement states for continuous variables. It discusses the relationship between the fidelity and the entanglement of EPR states, which is characterized by the degree of squeezing and the gain of classical channels. It shows that the quality of teleporting quantum states also depends on the characteristics of the states themselves. The properties of teleporting even and odd coherent states at different intensities are investigated. The difference of teleporting two such kinds of quantum states are analysed based on the quantum distance function.

Quantum Properties of Two-Mode Squeezed Even and Odd Coherent States

Two new types of quantum states are constructed by applying the operator s（ξ） = exp（ξ＊ ab - ξa＋b＋） on the two-mode even and odd coherent states. The mathematical and quantum statistical properties of such states are investigated. Various nonclassical features of these states, such as squeezing properties, the inter-mode photon bunching, and the violation of Cauchy-Schwarz inequality, are discussed. The Wigner function in these states are studied in detail.

Quasiprobability distributions of new kinds of even and odd nonlinear coherent states

Using a numerical computational method, quasiprobability distributions of new kinds of even and odd nonlinear coherent states （EONLCS） are investigated. The results show that the distributions of the new even nonlinear coherent states （NLCS） are distinct from those of the new odd NLCS and imply that the new EONLCS always exhibit some different nonclassical effects. Finally, with the aid of newly introduced intermediate coordinate-momentum representation in quantum optics, the tomograms of the new EONLCS are calculated. This is a new way of obtaining the tomogram function.

Finite-dimensional even and odd nonlinear pair coherent states and their some nonclassical properties

In this paper a new class of finite-dimensional even and odd nonlinear pair coherent states （EONLPCSs）, which can be realized via operating the superposed evolution operators D±（τ） on the state ｜q, 0）, is constructed, then their orthonormalized property, completeness relations and some nonclassical properties are discussed. It is shown that the finite-dimensional EONLPCSs possess normalization and completeness relations. Moreover, the finite-dimensional EONLPCSs exhibit remarkably different sub-Poissonian distributions and phase probability distributions for different values of parameters q, η and ξ.

Properties of Phase and Their Evolutions in Damped Odd and Even Coherent States

The properties of measured phase operators in damped odd and even coherent states have been studied. The fluctuations associated with measured phase and their squeezing in these states are investigated. The phase properties in damped superposition coherent states are considered too with the help of measured phase operators. These fluctuations and their squeezing are affected by damping and evolve with time elapsing.

Amplitude-squared squeezing of the generalized odd-even coherent states of the anharmonic oscillator in a finite-dimensional Hilbert space

This paper discusses the properties of amplitude-squared squeezing of the generalized odd-even coherent states of anharmonic oscillator in finite-dimensional Hilbert space. It demonstrates that the generalized odd coherent states do exhibit strong amplitude-squared squeezing effects in comparison with the generalized even coherent states.

Superposition Coherent States and Their Properties

Special kinds of generalized superposition states, superposition coherent states, are studied in this paper. These states can be produced by superposing a pair of coherent states ｜ α 〉 and ｜- α 〉. Their quantum statistical properties, the fluctuations of field and squeezing have been discussed in detail. These properties are dependent on superposition phase. We also describe the squeezing regions in phase space for these states.

Kerr介质中V型三能级原子与压缩相干态光场相互作用系统Mandel因子的演化特性

研究了在充满Kerr介质的高Q腔中V型三能级原子与压缩相干态光场相互作用系统Mandel因子Q(t)的时间演化规律;讨论了Kerr介质强度系数μ、光场压缩因子γ、光场相干振幅分量模平方|α|2和原子-场的耦合系数λ对光子统计分布特性的影响。结果发现:μ、γ、|α|2和λ都影响了Mandel因子Q(t)演化曲线量子崩塌-复苏效应的周期性,同时,也影响了受激辐射场的光子统计分布的状态和特性。

奇偶相干态信号场下的量子关联和纠缠

为了实现两原子之间的非经典关联,借助于电磁诱导光透明(electromagnetically induced optical transparency,EIT)机制,利用量子态的映射技术,研究原子系综内两原子的量子关联和纠缠。结果表明:分别通过测量扰动刻画的量子关联和并发度刻画的量子纠缠,发现它们都能够被绝热地生成,但是,随着平均光子数的增加,二者的演变完全不同。随着平均光子数的增加,无论信号场是奇数相干态还是偶数相干态,它们都有利于量子关联的生成。对于奇相干态信号场,量子纠缠随着光子数的增加而逐渐减小;对于偶相干态信号场,量子纠缠却经历了一个先增加后减小的过程。系综内原子个数的增加,使得原子间的退相干加剧,从而导致量子关联和纠缠都被削弱。

Dynamics of Nonclassicality of Time-and Conductivity-Dependent Squeezed States and Excited Even/Odd Coherent States

Recently, the quantum description of electromagnetic waves in conducting media has been performed. It has been demonstrated that in particular case, the Hamiltonian of the corresponding field can be expressed by Caldirola–Kanai Hamiltonian. In this paper, using the associated annihilation and creation operators of the above-mentioned quantized field, the time-and conductivity-dependent squeezed vacuum and one-photon squeezed states as well as their superpositions, and also the time-and conductivity-dependent excited even and odd coherent states are produced. Also,using a few well-known nonclassicality criteria, the time evolution of nonclassicality features of the above classes of obtained states, in addition to the influence of medium conductivity on them are demonstrated, numerically. It has been shown that the nonclassicality indicators may be adjusted by tuning the conductivity of media.

Kerr偶奇相干态及其非经典性

本文对Ｋｅｒ偶奇相干态及其非经典性质进行了研究．结果表明：Ｋｅｒｒ偶相干态可呈现周期性的二阶压缩效应，Ｋｅｒｒ奇相干态则不存在这种压缩效应；但两者均可呈现周期性的振幅平方压缩效应，这与通常偶奇相干态的情形有所不同．

Kerr介质中级联三能级原子与压缩相干态相互作用的光子统计演化

本文研究了存在Kerr介质的高Q腔中压缩相干态与级联三能级原子相互作用的光子统计演化规律，讨论了光场参数、Kerr介质及相干振幅对平均光子数的影响．

Kerr介质中三能级原子与压缩光场相互作用的光子统计分布特性

本文研究了充满Ｋｅｒ介质的高Ｑ腔中压缩相干态与级联三能级原子相互作用的光子统计分布特性。

Kerr介质中双模奇偶纠缠相干光场与V型三能级原子相互作用系统的光子统计性质

采用求解Schr(?)dinger方程和数值计算方法,研究了Kerr介质中双模奇偶纠缠相干光场与V型三能级原子相互作用系统的光子统计性质,分析了双模奇偶纠缠相干光场的纠缠度、Kerr介质与光场的耦合强度、双模光的平均光子数、失谐量和原子基态概率幅对光子统计性质的影响。结果表明:双模奇偶纠缠相干光场的纠缠程度对光子统计性质的影响不十分明显;Kerr效应增强使演化曲线上下移动,曲线的振荡频率变大、振荡幅度变小;保持场模1的光子数不变而改变场模2的光子数,会使演化曲线向上或向下显著移动、曲线的振荡幅度发生变化;失谐量的改变对光子统计特性也有一定影响;原子初态中基态概率幅的变化使演化曲线上下显著移动。

kth-order antibunching effect for a new kind of excited even and odd q-coherent states

A new kind of excited even q-coherent states （aq^-1）^m｜α〉q^e and excited odd q-coherent states （aq^-1）^m｜α〉q^o is constructed by acting with inverse boson operators on the even and odd q-coherent states. The m dependence of the kth-order antibunching effect is numerically studied for k = 2, 3, 4, 5. It is shown that the kth-order antibunching effect enhances as m increases. The larger k, the quicker the antibunching effect enhances.

Kerr介质对双模光场压缩效应的影响

研究了在充满Kerr介质的高Q腔内三能级原子与双模光场相互作用系统中光场的压缩效应 ,分析了腔中Kerr介质对初态分别为双模压缩真空态和SU(1,1)相干态的两种光场的双模压缩以及双模和压缩的影响 ,指出了Kerr效应对初态为SU(1,1)

Kerr介质中双模纠缠相干光场与V型三能级原子相互作用系统的原子偶极压缩

研究了Kerr介质中双模纠缠相干光场与V型三能级原子相互作用系统的原子偶极压缩效应,结果表明:此压缩效应和双模纠缠相干光场的纠缠程度、Kerr介质与光场的耦合强度、失谐量及原子初态相关联。

Kerr介质中双模纠缠相干光场与Bell态原子相互作用系统的原子布居数演化

运用全量子理论和数值计算方法,研究Kerr介质腔中处于Bell态的两个全同二能级纠缠原子与双模纠缠相干光场相互作用系统的原子布居数演化特性.讨论了双原子体系的初态、初始光场的平均光子数、双模纠缠相干光场的纠缠程度及Kerr介质与双模光场的耦合强度对原子布居时间演化特性的影响.结果表明,当双原子体系的初态为β11〉时,原子布居均不随时间变化;当双原子体系的初态为β00〉,β01〉或β10〉且初始平均光子数达到一定值时,演化特性呈现周期性的崩塌-回复效应,并随初始光子数的增加,其演化曲线的振荡频率增大,振幅减小;双模纠缠相干光场的纠缠程度不影响Rabi振荡频率,但对振幅影响显著;Kerr介质与光场耦合系数达到一定值时,对Rabi振荡频率和幅度及原子布居的崩塌-回复周期产生强烈影响.