减光子偶、奇相干态及其量子统计特性

最近,XIN Zong-zheng等研究了玻色产生算符+重复作用k次下通常偶、奇相干态|α>e,o的光子激发态|α,+k>～+k|α>o,e的非经典特性[J. Phys. B29 1996) 2597]. 本文讨论|α>e,o在玻色产生算符的逆算符+-1重复作用于k次下的光子湮灭态|α,-k>～+-k|α>o,e的量子统计特性.     

一种新的偶奇非线性相干态中测量相位算符的压缩效应

利用Bamett和pegg提出的测量相位算符讨论了一种新的偶奇非线性相干态的压缩效应。结果表明，在这种偶奇非线性相干态中测量相位算符不存在CN和SN类压缩，只存在CS类压缩。利用数值计算方法研究了CS类压缩效应，结果表明与通常的偶奇相干态的不同的是，偶非线性相干态在大区域内出现压缩效应而奇非线性相干态在小区域内才出现压缩效应。     

增加光子对和减少光子对相干态的统计性质

引入增加光子对相干态|ζ,q;m >_a=a^+m|ζ,q >和减少光子对相干态|ζ,q;-m >_b=b^m|ζ,q >,研究了这些态所描写的光场的统计性质。结果显示当在对相干态的a模增加光子时,两模的平均光子数均增加,亚泊松分布性质增强;当在对相干态的b模取走光子时,b模的平均光子数减少,而a模的平均光子数却增加;b模的亚泊松分布性质减弱,而a模的亚泊松分布性质却增强。我们还计算了场模间的相关度和场模的压缩。     

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.     

相干态光场的位相统计性质

根据Pegg-Barnett位相定义，计算了相干态光场的位相概率分布函数，并且进行了数值模拟。研究表明在真空态时，位相分布曲线为一条直线；相干态下位相分布曲线表现为：均匀分布→泊松分布→均匀分布。     

增加光子纠缠相干态的统计性质

引入了增加光子纠缠相干态.研究了在纠缠相干态的某个模上加入光子对光场统计性质的影响.由于两个场模间的纠缠,在a模上加入光子不但可以使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(增加或减少).加入光子后,光场的亚泊松分布和压缩特征得到明显增强. 关键词： 纠缠 增加光子态 统计性质     

偶、奇相干态的光子湮灭态

最近 ,Zong ZhengXin等研究了玻色产生算符a∧ + 重复作用k次下通常偶、奇相干态 |α〉e,o的光子激发态 |α ,+k >～a∧ +k|α >o ,e的非经典特性 [3]。本文讨论 |α >e ,o在玻色产生算符的逆算符a∧+ -1的重复作用k次下的光子湮灭态 |α ,-k >～a∧+ -k|α >o,e的量子统计特性。     

增光子圆态及其性质

利用光场产生算符的逆算符作用于圆态来构造增光子圆态.讨论了此态的非经典性质,同时计算并模拟出它的维格纳(Wigner)函数.结果表明,在不同光强下,随着激发数的增大增光子圆态光场的平均光子数增加与减少交替地出现;光子激发后,光场的亚泊松统计特性得到增强,压缩效应却受到抑制.维格纳函数图像显示了增光子圆态显著的非经典性质,发现了光子激发与圆态光强的增大都能使量子态由叠加引起的干涉效应明显增强.另外,在不同叠加数的情况下,通过适当选择参量可使维格纳函数具有相同的变化规律.     

增光子奇偶相干态的相位特性

借助于Pegg-Barnett相位算符理论和数值计算方法,研究了增光子奇偶相干态的相位概率分布,在此基础之上,讨论了有关数算符和相位算符的压缩特性。结果表明,增光子奇偶相干态的相位概率分布与通常的奇偶相干态、非线性相干态不同,在这种新的奇偶相干态中,其Pegg-Barnett相位概率分布能明显地反映出不同的量子相位信息和干涉特性。同时发现,在参量α的某些不同的取值范围内,增光子奇偶相干态在数算符和相位算符分量上均存在压缩效应。     

相干态是a^—1的本征态码

对“谐振子产生算符和湮没算符的逆算符”一中的一个结论提出不同的看法，我们证明，相干态（Ｚ）并不是湮没算符算符ａ＾－１的本征态，ａ＾－１│Ｚ）实际上是一个完全不同于│Ｚ）的新量子态。     

Nonlinear Quantum Optical Springs and Their Nonclassical Properties

The original idea of quantum optical spring arises from the requirement of quantization of the frequencyof oscillations in the Hamiltonian of harmonic oscillator. This purpose is achieved by consideringa spring whose constant (and so its frequency) depends on the quantum states of another system.
Recently, it is realized that by the assumption of frequencymodulation ofω toω(1+μa^\dagger a)^1/2the mentioned idea can be established.
In the present paper, we generalize the approach of quantum optical springwith particular attention to thedependence of frequency to the intensity of radiation fieldthatnaturally observes in thenonlinear coherent states}, from which we arrive ata physical system has been called by us as nonlinear quantum optical spring.Then, after the introduction of the generalized Hamiltonian of nonlinear quantum optical spring and it's solution,we will investigate the nonclassical properties of the obtained states. Specially, typical collapse and revivalin the distribution functions and squeezing parameters, as particular quantum features, will berevealed.     

Production of the Superposition of Nonlinear Coherent States and Entangled Nonlinear Coherent States

In this paper, by using the parity operator as well as the nonlinear displacement-type operator, we define new operators which by the action of them on the vacuum state of the radiation field, superposition of two nonlinear coherent states and two-mode entangled nonlinear coherent states are generated. Also, we show that via the generalization of the presented method, the superposition of more than two nonlinear coherent states and n-mode entangled nonlinear coherent states can be generated.     

New Even and Odd Nonlinear Coherent States and Their Nonclassical Properties

Based on Roy and Roy's work (Roy, B. and Roy, P. (2000). Journal of Optics B: Quantum Semiclass. Opt. 2, 65), a new type of even and odd nonlinear coherent states (NCSs) are defined. They result from Schrödinger cat states for deformed field. Using the numerical method, we study nonclassical properties of the new even and odd NCSs. It is shown that quantum statistical properties of the new even and odd NCSs are quite different from those of the usual even and odd coherent states (CSs). It is found that the squeezing only consists in the new even NCS, and the amplitude-squared squeezing and antibunching effect appear for both new even and odd NCSs in some ranges of ||.     

Study of Concurrence and D-Concurrence on Two-QubitsResulted in Pair Coherent States in Language of SU(2) Coherent States

Pair coherent state, is a state of a two-mode radiation field that is known as a state with non-gaussian wave function. In this paper, study on the pair coherent state, we notice that with superposition of two first terms of this states, one two-qubits formed. Because of the importance of two-qubits in theory of quantum entanglement, with two different measures with the title of concurrence and D-concurrence, we have studied the amount of entanglement and
discussed its details. At the end, we describe these measures for pair coherent states as a function of the amplitude of the SU(2) coherent states.     

Nonlinear Coherent States and Some of Their Properties

We construct nonlinear coherent states by the application of a deformed displacement operator acting upon the vacuum state and as approximate eigenstates of a deformed annihilation operator. These states are used to evaluate the temporal evolution of the average value of the momentum and the diplacement coordinate as well as their dispersions. We also construct even and odd combinations of these nonlinear coherent states and compute their second order correlation function in order to analyze their statistical behavior.     

Generalized Weyl Ordering and Nonlinear Coherent States

In the context of the nonlinear coherent state (NLCS) theory we introduce the generalized Weyl orderingoperator formulation. The corresponding generalized Wigner operator turns out to be the Weyl ordered Dirac δ-operatorfunctions. The completeness relation of NLCS is recast into generalized Weyl ordering form. The relationship betweennormal ordering, antinormal ordering and the generalized Weyl ordering is established which constitute a self-consistenttheory for NLCS.     

q变形对相干态及其反聚束效应

利用q变形玻色产生算符和湮没算符及其逆算符的性质，引入了q变形的两种对相干态，研究了q变形对相干态的反聚束效应和两模间的关联特性. 结果表明，q变形对相干态呈现反聚束效应，两模的光子相互关联，并且q参数对这些非经典特性的调节比较明显，随着q偏离1越大，这些特性越明显.     

Generalized Weyl Ordering and Nonlinear Coherent States

In the context of the nonlinear coherent state(NLCS)theory we introduce the generalized weyl ordering operator formulation.The corresponding generalzied wigner operator turns out to be the Weyl ordered diracδ-operator functions.The completeness relation of NLCS is recast into generalized Weyl ordering form,The relationship between normal ordering,antinormal ordering and the generalized Weyl ordering is established which constitute a self-consistent theory for NLCS.     

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.     

奇偶对相干态的维格纳函数和层析图函数

利用纠缠态η〉表象下的维格纳算符,重构了奇偶对相干态的维格纳函数.根据维格纳函数在相空间中随变量ρ和γ的变化规律,讨论了奇偶对相干态的非经典性质和量子干涉效应.研究发现,奇偶对相干态总呈现非经典性质,并且当q取奇数时,奇偶对相干态更容易出现非经典性质.奇偶对相干态的量子干涉效应的显著程度与q取值有关,但对于q的同一取值,奇对相干态的量子干涉效应更为显著.利用纠缠态η〉表象下的维格纳算符Δ1,2(ρ,γ)和纠缠态η,τ1,τ2〉的投影算符之间满足的拉东变换,获得了奇偶对相干态的量子层析图函数.