Statistical Properties of Photon-Added Two-Mode Squeezed Coherent States

The nonclassical and non-Gaussian quantum states—photon-added two-mode squeezed coherent states have been theoretically introduced by adding multiple photons to each mode of the two-mode squeezed coherent states. Starting from the new expression of two-mode squeezing operator in entangled states representation, the normalization factor is obtained, which is directly related to bivariate Hermite polynomials. The sub-Poissonian photon statistics, cross-correlation between two modes, partial negative Wigner function are observed, which fully reflect the nonclassicality of the target states. The negative Wigner function often display non-Gaussian distribution meanwhile. The investigations may provide experimentalists with some better references in quantum engineering.     

Entanglement Properties of Two-Mode Squeezed Coherent States in Radiation Field

Entanglement properties of two-mode squeezed coherent states in the radiation field are investigated according to the entanglement criterion [Phys. Rev. Lett. 84 (2000) 2722]. The dependence of entanglement on squeeze angle and squeeze parameter is discussed. It shows that the system evolves into entangled states and entanglement does not increase persistently with the increase of squeeze angle and squeeze parameter. There only exists a certain squeeze angle in which the entanglement exists continuously.     

Generalized Two-Mode Squeezed States and Some Nonclassical Characteristics

A class of generalized two-mode squeezed states |φ〉 is presented, which are generated from the generalized two-mode squeezing operator U(γ,λ) acting on the two-mode coherent state |α ₁,α ₂〉. We first investigate some mathematical properties of U(γ,λ) including the squeezing transformation under U(γ,λ), ket-bra integral form in the coordinate representation, normally ordered form. Then we evaluate some nonclassical characteristics of the state |φ〉 such as higher-order squeezing behavior, entanglement analysis and analytical expression of the Wigner 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.     

Entanglement of Two-Mode Squeezed Even and Odd Coherent States

The two-mode squeezed even and odd coherent states are quantum states with some non-classical properties. The entanglement of two-mode squeezed even and odd coherent states are measured by non-classicality of P-function and separability inequalities of EPR-operators.     

Entanglement of Two-Mode Squeezed Even and Odd Coherent States

The two-mode squeezed even and odd coherent states are quantum states with some non-classical properties. The entanglement of two-mode squeezed even and odd coherent states are measured by non-classicality of P-function and separability inequalities of EPR-operators.     

Nonclassical Properties of Squeezed Finite-Dimensional Pair Coherent State

We study the effect of the squeeze operator on the finite pair-coherent state. The state is a type of a correlated two-mode state in finite dimension based on the resonant ion-cavity interaction. We have discussed some statistical properties for such state, especially the quadrature variances as well as the second-order correlation function. Furthermore we have also considered the variance in the photon number sum and difference in addition to the linear correlation function. It is shown that the strong correlation occurs for a large value of the photon number difference. Our discussion is extended to include the quasiprobability distribution functions (W-Wigner and Q-functions). In the meantime we have considered the quadrature distribution function and phase distribution. It has been shown that the squeezed finite pair coherent state is sensitive to the variation in the state parameter, ξ and the squeeze parameter, r, as well as the q parameter which in fact plays a crucial role of controlling the behavior of the system.     

Nonclassical Properties of Excited Entangled Coherent States

Single-mode excited entangled coherent states (SMEECSs) is a new kind of continuous-variable-type entangled pure states. In this paper, we investigate nonclassical properties of the SMEECSs, and focus on discussing the influence of photon excitations on quantum statistics. It is shown that the photon excitations excitated the nonclassical character amount of the SMEECS for some certain cases.     

Nonclassical Properties of Photon-Added Pair Coherent States

After analyzing the course of forming‘garbageblocks’,we proposed an alternative for preparing the pseudo-pure states.It can be used to reduce or even to remove the‘garbageblocks’.     

Decoherence and Fidelity in Teleportation of Coherent Photon-Added Two-Mode Squeezed Thermal States

We theoretically introduce a kind of non-Gaussian entangled resources, i.e., coherent photon-added two-mode squeezed thermal states (CPA-TMSTS), by successively performing coherent photon addition operation to the two-mode squeezed thermal states. The normalization factor related to bivariate Hermite polynomials is obtained. Based upon it, the nonclassicality and decoherence process are analyzed by virtue of the Wigner function. It is shown that the coherent photon addition operation is an effective way in generating partial negative values of Wigner function, which clearly manifests the nonclassicality and non-Gaussianity of the target states. Additionally, the fidelity in teleporting coherent states using CPA-TMSTS as entangled resource is quantified both analytically and numerically. It is found that the CPA-TMSTS is an entangled resource of high-efficiency and high-fidelity in quantum teleportation.     

Photon Statistics of Generic Two-Mode Squeezed Coherent Light

for two-mode squeezed coherent states, the photon distribution function is expressed in terms of both four-variable and two-variable Hermite polynomials depending on two squeezing parameters, the relative phase between the two oscillators, their “spatial” orientation, and a four-dimensional shift in phase space of the electromagnetic field oscillator. The oscillations of the photon distribution function are discussed. The Wigner function and Q-function of the generic two-mode squeezed vacuum and squeezed coherent state are calculated explicitly.     

Nonclassicality and Entanglement of Photon-Subtracted Two-Mode Squeezed Coherent States Studied via Entangled-States Representation

We theoretically introduce a kind of non-Gaussian entangled states, i.e., photon-subtracted two-mode squeezed coherent states (PSTMSCS), by successively subtracting photons from each mode of the two-mode squeezed coherent states. The normalization factor which is related to bivariate Hermite polynomials is obtained by virtue of the two-mode squeezing operator in entangled-states representation. The sub-Poissonian photon statistics, antibunching effects, and partial negative Wigner function, respectively, are observed numerically, which fully reflect the nonclassicality of the resultant states. Finally, employing the SV criteria and the EPR correlation, respectively, the entangled property of PSTMSCS is analyzed. It is shown that the photon subtraction operation can effectively enhance the inseparability between the two modes.     

相干态与压缩态迭加的量子特性

基于量子力学基本理论,构造了一个由相干态与单模压缩态构成的新迭加态:|φ>=N(|α> eiψ|β>g);详细讨论了其压缩效应和光子数反聚束效应,发现该迭加态呈现出多样的量子特性.在按类似奇偶相干态的方式迭加时,迭加态具有奇偶相干态和压缩奇偶相干态的某些特性.作为特例,当压缩因子为0时,可以得到奇偶相干态和相干态.     

Properties of Entropy and Entanglement of Two-Mode Nonlinear Coherent States

In this communication, two-mode nonlinear coherent states are reviewed and special cases are given.Starting from a three-level atom coupled to two modes of radiation with any form of nonlinearities of the two-modefields, we derive a Raman-coupled effective Hamiltonian by a unitary transformation, evaluated perturbatively in couplingconstants. We use the quantum entropy to measure the degree of entanglement in the time development of an effectivetwo-level atom interacting with two-mode nonlinear-coherent states. The results show that the nonlinearity effect yieldsthe superstructure of atomic Rabi oscillations and the effect of the Stark shift changes the quasiperiod of the field entropyevolution and entanglement between the particle and the field. A possible experimental test of a new effect is proposed.     

Entanglement Swapping for Displaced Two-Mode Squeezed States

We discuss the entanglement swapping of two pairs of displaced two-mode squeezed states and find that the squeezing parameter of the outcoming squeezed state is less than that of the originM squeezed states. The calculation is greatly simplified by virtue of the natural expression of the two-mode squeezing operator in EPR eigenstate representation. A protocol for such entanglement swapping is proposed.``     

Multiple-Photon-Added and -Subtracted Two-Mode Binomial States:Nonclassicality and Entanglement *

We theoretically analyze the nonclassicality and entanglement of two new non-Gaussian entangled states generated by applying multiple-photon addition and subtraction to a two-mode binomial state. The nonclassical properties are investigated in terms of the partial negativity of the Wigner functions, whose results show that their nonclassicality can be enhanced via one-mode even-number photon operations and two-mode symmetrical operations for the initial two-mode binomial state. We also find that there exists some enhancement in the entanglement properties in certain parameter ranges via one-mode photon-addition and two-mode symmetrical operations.     

双模激发压缩真空态的维格纳函数

利用纠缠态表象下的维格纳(Wigner)算符,构造了双模激发压缩真空态的维格纳函数,并根据该函数在相空间ρ-γ中随参量m,n和r的变化关系,讨论了双模激发压缩真空态的量子干涉特性和压缩效应。结果表明,对于参量m,n不同的取值,双模激发压缩真空态的量子干涉效应的强弱不同;而对于不同的压缩参量r,双模激发压缩真空态呈现出不同程度的压缩效应。最后,根据双模激发压缩真空态的维格纳函数的边缘分布,阐明了此维格纳函数的物理意义。     

双模压缩数态及参量放大器中的压缩对称性

得到了参量放大器哈密顿量与广义双模压缩算符共同本征的双模压缩数态。提出了压缩荷与压缩对称性的概念来解释哈密顿量在由广义压缩算符生成的一维么正群变换下的不变性。     

A Kind of Atomic Coherent State as a Two-Mode Squeezed State

We find that a kind of atomic coherent state, formed as exp[ ξJ＋-ξJ-]｜00〉,when the SU（2） generators J± are taken as Fan＇s form J＋=（1/2）（α1-α2）（α1-α2）,J-=（1/2）（α1＋α2）（α1＋α2）,and J0=（1/2）（α1α2-α1α2）,is simultaneously a two-mode squeezed state. We analyse this squeezed state＇s physical properites, such as the cross- correlation function, the Wigner function, and its marginal distribution as well as the Husimi function.