Amplitude-squared squeezing of superposition of coherent states

This paper discusses the amplitude-squared squeezing for the superposition of two coherent states with their phase differences being separately π/2, 3π/2, and π1, as well as for the superposition state of two pseudoclassical states. According to the analysis, it is found that the superposition state of two coherent states with their phase differences π/2 and 3π/2, and the superposition state of two pseudoclassical states both do exhibit the amplitude-squared squeezing. Also, some specific states are found to exhibit even stronger squeezing effects when relative phase of the superposition is equal to the average photon number. Amplitude-squared squeezing is dependent on the difference in phase between two coherent states.     

相干态的叠加态的量子统计性质

本文研究了相干态的叠加态的量子统计性质.结果表明,相干态的叠加态仅存在奇次幂的高阶压缩效应,而不存在偶次幂的高阶压缩效应.给出了高阶压缩和高阶反聚束效应与叠加系数间的函数关系.高阶压缩要求叠加系数的辐角取值满足cosθ>exp(-2|α|²),而高阶反聚束效应则要求0.5π<θ<1.5π.奇偶相干态的有关结果均作为特例应包含在本文的一般结论之中.     

非Lamb-Dicke近似下制备囚禁冷离子的振动相干态

根据非Lamb-Dicke近似下激光-离子相互作用动力学规律,讨论了如何利用一系列的激光脉冲来驱动冷离子,从而从运动基态出发获得一系列振动数态的宏观叠加态.具体研究了这些叠加态的Q函数、Wigner函数和它们的非经典特性,如压缩和反群聚效应等.结果表明,合适地调节各个所用激光的脉冲长度,所产生的叠加态能很好地逼近熟知的振动相干态. 关键词： Lamb-Dicke近似 叠加态 相干态 非经典特性     

Superposition of two coherent states π out of phase with average photon number as relative phase

This paper discusses nonclassical features of the superposition of two coherent states π out of phase with each other and parameterized solely by amplitude α, that is, when the relative phase has a relationship with average photon number ∣α∣². In particular, it discusses oscillatory and sub-Poissonian photon statistics, degree of quadrature squeezing, and quasiprobability distribution functions. We examine that some nonclassical properties of these states are different from those of the even and odd coherent states.     

任意两个相干态的叠加及其量子统计性质

研究了由两个任意相干态构成的叠加态｜ψ〉=a｜β〉+be^iφ｜mβe^iδ 〉的量子统计性质，结果表明此种叠加态普遍存在着压缩效应或光子反群聚效应.叠 加态的量子效应依赖于β²和振幅系数m，同时改变相干态间的位相差δ和叠加 系数间的位相差φ也将对叠加态的压缩效应或反群聚效应起着重要的作用. 关键词： 相干态 叠加态 压缩效应 反群聚效应     

利用V型三能级原子与单模光场的非共振相互作用制备压缩相干态的叠加态

介绍了单模压缩相干态及其基本性质,根据简并V型三能级原子与单模光场的改进型有效哈密顿量,通过矩阵方法推导出原子-光场系统的态矢量.提出利用简并V型三能级原子与单模光场的非共振相互作用制备压缩相干态的叠加态的一种新方案,讨论了怎样进行控制单模压缩相干态光场中的压缩方向问题.     

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.     

一种新的非线性叠加相干态的相位特性

根据Pegg-Barnett 相位定义,计算了一种新的非线性叠加相干态的相位概率分布函数和光子数-相位压缩效应,并进行了数值模拟.     

q-形变的非简谐振子广义相干叠加态的高阶压缩效应

研究了q-形变的非简谐振子的广义相干态的高阶压缩效应,给出了出现高阶压缩现象的条件.     

增光子二模纠缠相干态的纠缠特性及其通过腔量子电动力学的制备

分析了增光子二模纠缠相干态的纠缠特性,得到共生纠缠度的解析表示式.结果表明:增光子二模纠缠相干态的共生纠缠度与叠加态的相位有非常灵敏的关系.提出了一种制备增光子相干态和增光子二模纠缠相干态的方法,其制备过程为首先把增光子相干态转化为相干态与真空态一种特殊的叠加态(叠加系数与相干态振幅有关),再通过位于高Q腔内的原子与经典激光场的相互作用,从而实现增光子相干态的制备.通过一个飞行原子先后与两个光腔中光场相互作用可以实现增光子二模纠缠相干态的制备.     

增光子二模纠缠相干态的纠缠特性及其通过腔量子电动力学的制备

分析了增光子二模纠缠相干态的纠缠特性,得到共生纠缠度的解析表示式.结果表明:增光子二模纠缠相干态的共生纠缠度与叠加态的相位有非常灵敏的关系.提出了一种制备增光子相干态和增光子二模纠缠相干态的方法,其制备过程为首先把增光子相干态转化为相干态与真空态一种特殊的叠加态(叠加系数与相干态振幅有关),再通过位于高Q腔内的原子与经典激光场的相互作用,从而实现增光子相干态的制备.通过一个飞行原子先后与两个光腔中光场相互作用可以实现增光子二模纠缠相干态的制备.     

原子薛定谔猫态中角动量的压缩及其时间演化

在低Q值腔内，原子相干态在一些特定时刻可以演化为原子薛定谔猫态.讨论了在这种原子薛定谔猫态中原子角动量的涨落和高阶涨落.根据不确定性原理，进一步研究了原子角动量的压缩和高阶压缩性质及其演化.研究表明，原子薛定谔猫态可以被压缩到二阶和六阶，但不能被压缩到四阶.当原子薛定谔猫态中被叠加的原子相干态数为无限多项时，其压缩特性与原子相干态相同. 关键词： 原子相干态 薛定谔猫态 角动量压缩 Bloch态     

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 ||.     

叠加qs相干态的非经典性质

构造了叠加qs相干态,并研究了它的压缩性质、反聚束效应等非经典性质.数值计算了叠加系数和形变参数q与s对非经典性质的影响.奇偶qs相干态的有关结果作为特例包含在本文的一般结论之中.     

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.     

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。     

一类q变形广义相干叠加态的量子统计性质

研究了一类q变形广义相干态叠加态|ψ>=a|β>+be^iφ|βe^iδ>的量子统计性质，结果表明此种叠加态普遍存在压缩效应和光子反群聚效应.相干态间的位相差，叠加系数的位相差和广义相干态之间内积的幅值和位相的变化对迭加态的压缩效应和反群聚效应起着重要的作用. 关键词： q变形')" href="#">q变形 广义相干态 压缩效应 反群聚效应     

Properties and Generation of Photon-Added Schrdinger Cat States

We have investigated the intensity squeezing of superposition of two photon-added coherent states and proposed a new method for preparation of photon-added coherent states and their superposition states.This method is based on interaction of the trapped ion with the traveling wave light fields with different frequencies.     

The entropic squeezing of superposition of two arbitrary coherent states

In this paper the superpositions of two arbitrary coherent states ｜ψ〉 = α ｜β｜ ＋ be^iψ ｜mβe^iδ〉 are constructed by using the superposition principle of quantum mechanics. The entropic squeezing effects of the quantum states are studied. The numerical results indicate that the amplitudes, the ratio between the amplitudes of two coherent states, the phase difference between the two components and the relative phase of the two coefficients play important roles in the squeezing effects of the position entropy and momentum entropy.     

叠加激发对相干态的非经典特性

从激发对相干态出发,构造了叠加激发对相干态,研究了该叠加态的非经典特性.结果表明:在一定条件下,随着相位的变化,叠加态场模的平均光子数呈现类似于拉比振荡的坍塌与复原现象,与激发对相干态相比,在叠加激发对相干态中亚泊松光子统计特性和CauchySchwatz不等式的破坏都得到了增强,但正交相位分量的压缩减弱.