Comparison of nonclassicality between photon-added and photon-subtracted squeezed vacuum states

In this paper, we introduce photon-added and photon-subtracted squeezed vacuum state （PASV and PSSV） and obtain their normalized factors, which have the similar forms involved in Lengendre polynomials. Moreover, we give the compact expressions of Wigner function, which are related to single-variable Hermite polynomials. Especially, we compare their nonclassicality in terms of Mandel Q-factor and the negativity of Wigner function.

Decoherence of photon-subtracted squeezed vacuum state in dissipative channel

This paper investigates the decoherence of photo-subtracted squeezed vacuum state （PSSVS） in dissipative channel by describing its statistical properties with time evolution such as Wigner function, Husimi function, and tomogram. It first calculates the normalization factor of PSSVS related to Legendre polynomial. After deriving the normally ordered density Operator of PSSVS in dissipative channel, one obtains the explicit analytical expressions of time evolution of PSSVS＇s statistical distribution function. It finds that these statistical distributions loss their non-Gaussian nature and become Gaussian at last in the dissipative environment as expected.

Wigner function and density operator of the photon-subtracted squeezed thermal state

By using the technique of integration within an ordered product of operators, the normal ordered density operator of the photon-subtracted squeezed thermal state （PSSTS） is derived. Then the corresponding Wigner function is presented by using the coherent state representation of the Wigner operator. The nonclassical properties of the PSSTS are discussed based on the negativity of the Wigner function.

Statistical properties of coherent photon-subtracted two-mode squeezed vacuum and its application in quantum teleportation

We introduce a kind of non-Gaussian entangled state, which can be obtained by operating a non-local coherent photon-subtraction operation on a two-mode squeezed vacuum. It is found that its normalization factor is only related to the Legendre polynomials, which is a compact expression. Its statistical properties are discussed by the negative region Wigner function with the analytical expression. As an application, the quantum teleportation for coherent states is considered by using the non-Gaussian state as an entangled channel. It is found that the teleportation fidelity can be enhanced by this non-Gaussian operation.

Nonclassicality of photon-added squeezed vacuum states

By applying the bosonic creation operator to squeezed vacuum states, this paper introduces a new kind of quantum states： photon-added squeezed vacuum states. It also presents an experimental approach to prepare these states, and investigates their quantum statistical properties by the numerical method. The results indicate that these states reveal some interesting non-classical properties, such as anti-bunching effects, squeezing effects and negativities of the relevant Wigner functions.

New formulas for normalizing photon-added(-subtracted) two-mode squeezed thermal states

For the first time,we derive the compact forms of normalization factors for photon-added（-subtracted） two-mode squeezed thermal states by using the P-representation and the integration within an ordered product of operators（IWOP） technique.It is found that these two factors are related to the Jacobi polynomials.In addition,some new relationships for Jacobi polynomials are presented.

Photon number cumulant expansion and generating function for photon added-and subtracted-two-mode squeezed states

For the first time, we derive the photon number cumulant for two-mode squeezed state and show that its cumulant expansion leads to normalization of two-mode photon subtracted-squeezed states and photon added- squeezed states. We show that the normalization is related to Jacobi polynomial, so the cumulant expansion in turn represents the new generating function of Jacobi polynomial.

PHOTON-SUBTRACTED(-ADDED) THERMO VACUUM STATE AND THEIR APPLICATION IN JACOBI POLYNOMIALS

We construct photon-subtracted(-added)thermo vacuum state by normalizing them.As their application we derive some new generating function formulas of Jacobi polynomials,which may be applied to study other problems in quantum mechanics.This will also stimulate the research of mathematical physics in the future.

Thermal vacuum state corresponding to squeezed chaotic light and its application

For the density operator（mixed state） describing squeezed chaotic light（SCL） we search for its thermal vacuum state（a pure state） in the real-fictitious space. Using the method of integration within ordered product（IWOP） of operators we find that it is a kind of one- and two-mode combinatorial squeezed state. Its application in evaluating the quantum fluctuation of photon number reveals： the stronger the squeezing is, the larger a fluctuation appears. The second-order degree of coherence of SCL is also deduced which shows that SCL is classic. The new thermal vacuum state also helps to derive the Wigner function of SCL.

Two-Mode Excited Squeezed Vacuum State and Its Properties

In this paper, the two-mode excited squeezed vacuum state （TESVS） is studied by using the statistical method. By calculating the normalization of the TESVS, a new form of Jacobi polynomials and some new identities are obtained. The photon number distribution of the TESVS is given and it is a simple form of Jacobi polynomials. Using the entangled state representation of Wigner operator, the Wigner function of the TESVS is obtainded and the variations of the Wigner function with the parameters m, n, and r are discussed. Here from the phase space point of view the TESVS can be well interpreted and described.

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.

叠加激发双模压缩真空态的量子统计特性(英文)

从激发双模压缩真空态 a mb m| ξ〉出发构造了叠加态 | Ψ〉,研究了 | Ψ〉的量子统计特性 .结果表明 :在一定的条件下 ,随着相位差的变化 ,叠加态 | Ψ〉的平均光子数出现类似于Rabi振荡的崩塌与复原现象 ,而且与单个激发双模压缩真空态 a mb m|ξ〉相比 ,在叠加态

增加光子对和减少光子对相干态的等阶Y压缩效应

通过数值计算,研究了增加光子对相干态|,ξq;m〉A=a+m|,ξq〉和减少光子对相干态|,ξq;-m〉S=bm|,ξq〉的等阶Y压缩效应.结果表明:对于增加光子对相干态a+m|,ξq〉和减少光子对相干态bm|,ξq〉,光场都存在着等阶K(=2,3,4,5…)次方Y压缩效应,但是增加a模的光子或取走b模的光子,即随着场模上光子增加(减少)数m的增大,二者的等阶K次方Y压缩效应均减弱,且有相似的曲线变化规律.

增、减光子压缩真空态的维格纳函数及其非经典特性

利用Fock态表象下的维格纳(Wigner)函数表示式,重构增、减光子压缩真空态的维格纳函数;依据维格纳函数在相空间中的分布规律,讨论这些量子态的非经典特性.数值结果表明:增、减光子压缩真空态的维格纳函数均出现负值,它们都是具有非经典特性的量子态;这些量子态的维格纳函数与增、减光子数k的取值有关,k取奇数时函数的负性明显大于k取偶数时的状况.此结果为这些量子态的测量提供理论依据.

有效二能级原子与压缩真空态相互作用过程中原子和场的动力学特性

本文研究了初始辐射场为由ＳＵ（１，１）相干态描述的压缩真空态时，Ｓｔａｒｋ效应对双光子ＪａｙｎｅｓＣｕｍｍｉｎｇｓ模型中原子和场的压缩效应，以及光子的反聚束效应的影响。作为比较，本文也讨论了初始辐射场为相干态光场时原子和场的动力学特性。

增加光子双模压缩真空态的N次方H压缩效应

通过数值计算,研究了增加光子双模压缩真空态的N次方H压缩效应。结果表明:对于态,光场存在着N次方H压缩效应,而且对于高次方H压缩,在压缩参数较大时,随着场模上光子增加数的增大,N次方H压缩效应增强.

双模压缩真空态的H压缩特性

用数值计算的方法研究了双模压缩真空态|ξ〉=1coshr∑∞n=0(-eiθtanhr)n|n,n〉的K次方H压缩特性.结果表明:当θ满足一定条件时,光场存在着K次方H压缩效应(K=1,2,3,4,5,…);但是,随着方次K的升高,K次方H压缩效应有所减弱.

压缩真空态中二能级原子简并双光子过程的广义Bloch-Siegert频移

用密度算符主方程方法研究了一二能级原子与宽带压缩真空态光场的简并双光子相互作用。我们发现原子偶极矩随时间的变化与压缩真空态光场的压缩参数｜Ｍ｜有关。｜Ｍ｜存在一个阈值Γ４ｇ。阈值之下，原子偶极矩以共振频率振荡；阈值之上，原子偶极矩以三种不同的频率振荡，其中中心频率仍为共振频率，两边频是由中心频率频移而得，这种现象即广义Ｂｌｏｃｈ－Ｓｉｅｇｅｒｔ频移，频移量与压缩真空态场的压缩参数有关。产生广义Ｂｌｏｃｈ－Ｓｉｅｇｅｒｔ频移的原因是双光子过程中压缩真空态光场对原子具有一种“驱动作用”的结果。

光子扣除双模压缩相干态的压缩性质

在量子光学中,光子扣除是一种最为基本的非高斯操作。当光子扣除操作执行于光场的一般高斯型量子态-双模压缩相干态时,可以得到一种非高斯型量子态,即光子扣除双模压缩相干态。研究结果表明:对量子态的2个模扣除相同的光子数可以明显地增强双模压缩相干态的双模压缩以及和压缩效应,而对量子态的2个模扣除不同的光子数通常会削弱态的压缩性质。

宽带压缩真空下运动梯形三能级原子的稳态布居

本文主要研究了宽带压缩真空下,激光场驱动的梯形三能级原子的稳态布居.我们从系统的哈密顿量出发,利用波恩—马尔科夫近似,推导出了主方程,进而得到原子的光学布洛赫方程.对这个方程我们用数值计算的方法得出了其稳态解,通过图示法详细讨论了粒子布居iσi随拉比频率ε、双光子失谐Δ、相位、光场的平均粒子数N等参量的变化情况.