迭加态与压缩效应增强

本文运用量子力学态迭加原理,讨论由真空态和压缩态的迭加态获取更深压缩光场的可能性。结果表明,对弱场强浅压缩光场压缩加强效应非常显著;并且在迭加态中还呈现出反聚束的非经典效应。 关键词：     

相位差与一般相干迭加态压缩特性

研究一般相干态的迭加态|ψ＞=a|β＞ beiψ|mβeiδ＞的k次方压缩特性,结果表明:一般相干态的迭加态和量子涨落的k次方压缩,在m=1时可表为k≠2nπ/δ,此处n是整数;在m≠1时,压缩的次方数可以是偶数也可以是奇数;当δ=π时,无论m[m∈(0.∞)]取何值均存在奇次方压缩,当δ=π/2时,无论m取何值均存在奇次方压缩和偶次方压缩.这说明参数相位差δ对一般相干态的k次方压缩的次方数起关键性的作用.     

压缩迭加态及其特性

压缩迭加态是由迭加态通过压缩系统后产生的一种辐射经典态。这种具备了Ｗｉｇｎｅｒ相空间压缩和相干迭加压缩两种机制。详细讨论了这种压缩迭加态的量子统计性质及压缩特性。     

叠加压缩相干态的量子统计性质

研究了叠加压缩相干态的量子统计性质,给出了压缩和反聚束效应与叠加系数之间的关系。结果表明,叠加压缩相干态具有压缩和反聚束的现象。压缩奇偶相干态的有关结果均作为特例包含在本文的一般结论之中。     

q变形奇偶相干迭加态的量子特性

文章给出了ｑ变形的奇偶相干迭加态的表达式，并研究了相应的ｑ变形奇偶相干迭加态光场的Ｎ阶压缩效应。     

压缩奇偶相干态的量子统计性质

用压缩算子作用在奇偶相干态上即可得到压缩奇偶相干态.本文研究了这类量子态的统计特性.结果表明,压缩奇相干态和压缩偶相干态都能处于压缩状态,它们的光子亦都可能出现反聚束的现象.     

叠加激发相干态的量子特性

构造了2个强度相同位相不同的激发相干态的叠加态,并通过数值计算研究了该叠加态的反聚束效应和振幅平方压缩效应随激发光子数m、光场强度x和相位差θ的变化,结果表明:随激发光子数m和光场强度x增大,该量子态的振幅平方压缩均会加深;压缩效应与相位差θ有密切的关系;随光场强度x的增大和激发光子数m的增大,其反聚束效应减弱.     

利用原子干涉方法来制备压缩相干迭加态

在文中我们提出了一种基于原子干涉的方法产生压缩相干迭加态，由此方法产生的迭加态的位相及权重因子均可控制。     

q—形变迭加态的压缩特性

运用数值计算方法研究了ｑ－形变的真空态与ｑ－形变的奇偶相干态的迭加态的压缩特性。     

混合迭加态的高阶压缩

本文详细计算一般的混合迭加态中△a₁和△a₂的k阶矩,应用Bloch矢量方法详细讨论混合迭加态中的高阶压缩,描写并定量计算,各阶压缩的压缩区域及压缩条件,讨论最佳压缩的条件,指出在高阶压缩的迭加态中,两个正交的分量a₁和a₂在某些条件可望同时被压缩,最后,试图对迭加态压缩的本质作一些探讨。 关键词：     

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.     

Nonclassical Properties of Multiple-Photon-Added Two-Mode Squeezed Coherent States

We investigate how the photon addition operation affects the nonclassical properties of the non-Gaussian squeezed state generated by adding photons to each mode of the two-mode squeezed coherent state (TMSCS). By the generating function of two-variable Hermite polynomials, the compact expression of normalization factor is derived. We show that the fields in such states exhibit remarkable sub-Poissonian photon statistics. The photon addition operation can enhance the cross-correlation for appropriate combinations of several parameters involved in the TMSCS. Compared with that of TMSCS, the Wigner function of the photon–added TMSCS (PA-TMSCS) is modulated by a factor which is also related with two-variable Hermite polynomials. Such Wigner functions have some negativity regions and show a strong quantum mechanical interference. In addition, the normalization factor, Mandel’s Q parameter, cross-correlation function and Wigner functions are all sensitive to the compound phase involved in TMSCS.     

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.     

Quantum Statistical Properties of k-Quantum Nonlinear Coherent States

In our preceding work, a class of k-quantum nonlinear coherent states, i.e., the k eigenstates of the powers B^^k (k≥3) of the annihilation operator B^ =a^ 1/f(N^) of f-oscillators, are introduced. In this paper, we introduce a new kind of higher-order squeezing and an antibunching effect. The quantum statistical properties of the k states are studied. The result shows that the M-th order [M=(n 1/2)k; n=0, 1,...] squeezing effects exist in all of the k states when k is even. There is the antibunching effect in all of the k states.     

Quantum Statistical Properties of k-Quantum Nonlinear Coherent States

In our preceding work, a class of k-quantum nonlinear coherent states, i.e., the k eigenstates of the powersBk (k ≥ 3) of the annihilation operator B=-a1/f(N) of f-oscillators, are introduced. In this paper, we introduce a newkind of higher-order squeezing and an antibunching effect. The quantum statistical properties of the k states are studied.The result shows that the M-th order [M = (n 1/2)k; n = 0, 1,...] squeezing effects exist in all of the k states when kis even. There is the antibunching effect in all of the k states.     

Coherent States and Squeezed States in Interacting Fock Space

In this paper we study coherent states and squeezed states in one mode interacting Fock space.     

Controlled Quantum Teleportation of Superposed Coherent State Using GHZ Entangled Coherent State

Controlled quantum teleportation of superposed coherent states using GHZ entangled 3-mode coherent states is studied. Proposed scheme can be implemented experimentally using linear optical components such as a symmetric lossless beam splitter, two phase-shifters and two photon counters. Fidelity is found close to unity for appreciable mean number of photons in coherent states and is 0.99 for mean photon number equal to two.