减光子压缩真空态的反群聚效应

利用玻色产生算符的逆算符及玻色湮没算符作用于压缩真空态来构造减光子压缩真空态,并通过计算减光子压缩真空态的二阶关联函数来讨论它们的光子反群聚性质。数值计算结果表明,在两种情况下所得到的减光子压缩真空态当湮没光子数k为奇数时均呈现出群聚效应,而当k为偶数时呈现反群聚效应。所呈现的反群聚效应对应的压缩参量η的取值区间与湮没的光子数k有关,在玻色产生箅符的逆算符的作用下随着k的增加,反群聚效应对应的压缩参量η的取值区间扩大,在玻色湮没算符作用下则相反。同时,作出二阶关联函数随压缩参量η变化的曲线来描述减光子压缩真空态所呈现的反群聚效应的变化特性。     

玻色算符的逆算符及其相关的奇偶相干态

利用玻色算符的逆算符a^^-1和a^^+-1，定义了一类新的奇偶相干态 ，即增、减光子奇偶相干态.它们分别是算符为a^^-ka^^k+2,a^^+-ka ^²a^^+k的本征态，可由a^^-k和a^^+-k分别作用于通常的奇偶相干态来产生. 数值计算结 果表明，这类新的奇偶相干态都是非经典的光场态，它们都能呈现出光子反群聚效应 关键词： 玻色算符的逆算符 奇偶相干态 光子反群聚效应 量子压缩效应     

激发纠缠相干态的统计性质

将玻色湮灭算符的逆算符作用在纠缠相干态的一个模上得到激发纠缠相干态.该量子态是玻色湮灭算符的偶次幂本征态;由于两个场模间的纠缠,在a模上增加光子不但可以使a模的平均光子数增加,也可以使b模的平均光子数发生变化;当a模上增加光子后,两个场模的亚泊松分布特性和Cauchy-Schwartz不等式的破坏都得到了增强,但模间反关联度反而减弱.     

与q形变玻色算符逆算符相关的相干态及其量子统计性质

讨论了ｑ形变玻色算符的广义逆算符作用于ｑ－相干态所得到的两类量子态的数学及量子统计性质。结果表明，ｑ－相干态的光子激发态不存在压缩但呈现反聚束效应，而ｑ－相干态的光子湮灭态却存在压缩但不呈现反聚束效应。     

增、减光子奇偶相干态的Wigner函数

利用Fock态表象下的Wigner函数定义，重构了增、减光子奇偶相干态的Wigner函数，并据此 讨论了它们的非经典性质.结果表明：增光子奇偶相干态总呈现出非经典特征，而减光子奇 偶相干态分别仅在k为偶数和奇数时呈现出非经典特征. 关键词： 奇偶相干态 玻色算符的逆算符 Wigner函数     

多光子非线性过程中的振幅平方压缩

本文研究了多光子非线性光学过程中的振幅平方压缩,证明了K光子么正算符Sk(z)(K>2)对非真空相干态的作用在—级近似下会产生振幅平方压缩.以及Sk(z)(K>2,K≠4)对真空态的作用不会产生振幅平方压缩.发现4个光子么正算符S4(z)对真空态的作用可以产生振幅平方压缩,这表明振幅平方压缩是一种独立于二阶压缩、反聚束以及亚泊松统计分布的新的光场非经典效应.     

非简并双光子Jaynes-Cummings模型中贝尔非定域性的演化

基于赝自旋算符的关联所对应的贝尔算符期待值,研究了各种双模非经典态(纠缠相干态、对相干态以及双模压缩真空态)在非简并双光子Jaynes-Cummings模型中贝尔非定域性的动力学特性.结果表明:对于纠缠相干态,贝尔非定域性的演化与双模场平均光子数的大小息息相关;对于对相干态和双模压缩真空态,贝尔非定域性会在有限的时间内完全消失,之后又基本上复原到初始值,呈现出周期性振荡现象.     

光子消灭算符k次幂本征态的量子统计性质

详细讨论了光子消灭算符任意k农幂a~k的正交归一本征态的振幅m(m≤k)次暴压缩和反聚束两种基本非经典效应.     

双参数形变谐振子湮没算符高次幂本征态的反聚束效应

研究了双参数形变谐振子湮没算符高次幂(akqs,k≥3)本征态的反聚束效应,并就k=3的情况运用数值计算方法研究了双参数形变对该效应的影响.结果表明,在双参数形变相干态中谐振子强度x=｜α｜²的若干取值区间内,akqs的本征态均可呈现反聚束效应,并且明显地受到qs形变参数的影响.     

测量相位算符在压缩热场态中的压缩效应

利用Bannett和Pegg提出的测量相位算符讨论了压缩热场态中测量相位算符的压缩效应。结果表明测量相位算符在压缩热场态中存在CS类压缩，压缩特性与相干态参数幅角θ、平均光子数n^-和压缩参量r有密切的关系。随着n^-和r的增大，CS类压缩效应逐渐减弱，直至完全消失。另有计算表明测量相位算符在压缩热场态中不存在CN和SN类压缩。     

Photon-added and photon-subtracted displaced Fock states and their non-classical properties

A new kind of quantum optical state, photon-added and -subtracted displaced Fock states, is introduced by applying the inverse of bosonic creation and annihilation operators to displaced Fock states. The quantum statistical properties of these states are investigated by numerical methods. Numerical results indicate that these states reveal some interesting non-classical properties, such as anti-bunching effects, sub-Poisson distributions and negativities of their Wigner functions.     

Interaction of a Three-Level Atom and Field in a Squeezed Vacuum State with Added Photons: Quantum Phase and Nonclassical Properties

We present a detail study of the evolution of nonlocal correlations of an interacting quantum system comprising a three-level atom and a field mode initially prepared in a squeezed vacuum state with added photons. We compare the dynamical behavior of the quantum phase and entanglement by varying the number of photons added to the squeezed vacuum state. Furthermore, we examine the influence of the added-photon number and the squeeze parameter on the dynamical behavior of entanglement, quantum phase, and nonclassical properties of the field. Moreover, we explore the link between the quantum phase and the nonlocal correlation. Finally, we introduce an effective method to generate and maintain a high level of entanglement for this quantum system based on precise parameter ranges.     

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.     

Squeezed vacuum as an eigenstate of two-photon annihilation operator

We introduce the inverse annihilation and creation operatorsa ⁻¹ anda ^+-1 by their actions on the number states. We show that the squeezed vacuum exp(1/2;ξa ⁺²]|0> and squeezed first number state exp[1/2;ξa ⁺²]|n=1> are respectively the eigenstates of the operators (a ^†−1 a) and (aa ^+-1) with the eigenvalue ξ.     

Kerr介质中耦合双原子与双模压缩真空场相互作用系统的光子统计性质

研究了存在Kerr介质时，双模压缩真空场与耦合二能级原子相互作用系统中光子的统计性质，讨论了Kerr介质与光场的耦合强度、光场的初始压缩因子和原子的初态对光子统计性质的影响.数值计算结果表明，光子周期性地交替呈现聚束和反聚束效应，光场两模之间总是呈现正相关，并且这种相关为非经典相关；Kerr介质的影响使光场的二阶相干度演化曲线呈现周期性的崩塌-回复现象，随着Kerr效应的加强，崩塌-回复周期变短，以至消失. 关键词： Kerr介质 耦合双原子 双模压缩真空场 光子统计性质     

Two-mode Gaussian states as resource of secure quantum teleportation in open systems

For secure quantum teleportation (SQT) of coherent states two conditions are necessary to be fulfilled: Gaussian-state resources with two-way steering and teleportation fidelity higher than 2/3. We investigate and compare squeezed thermal states and squeezed vacuum states as initial resource states for SQT in an open quantum system, consisting of two uncoupled harmonic oscillators interacting with a thermal environment. The evolution of the open system is obtained in terms of the covariance matrix, by using the Gorini-Kossakowski-Lindblad-Sudarshan master equation. The SQT conditions are satisfied in a longer period of time in the case of initial squeezed vacuum states, therefore these states are better resource states for SQT than squeezed thermal states. We show that the admissible time for SQT decreases by increasing temperature, dissipation coefficient and average number of thermal photons, while for greater values of the squeezing parameter, SQT conditions are satisfied in a longer period of time.     

Photon statistical properties of photon-added two-mode squeezed coherent states

We investigate photon statistical properties of the multiple-photon-added two-mode squeezed coherent states(PATMSCS).We find that the photon statistical properties are sensitive to the compound phase involved in the TMSCS.Our numerical analyses show that the photon addition can enhance the cross-correlation and anti-bunching effects of the PATMSCS.Compared with that of the TMSCS,the photon number distribution of the PA-TMSCS is modulated by a factor that is a monotonically increasing function of the numbers of adding photons to each mode;further,that the photon addition essentially shifts the photon number distribution.