共查询到19条相似文献,搜索用时 140 毫秒
1.
We consider the quantum superposition of two coherent states shifted in phase by 3π/2 |α〉 and | -iα〉, as well as special states that are characterized solely with respect to amplitude α. According to analysis of nonclassical properties such as oscillatory and sub-Poissonian distribution of photon numbers, photon antibunching, quadrature squeezing, and negativity of Wigner function, it is concluded that the considered superposition state is a nonclassical state. Also, the special state is found to exhibit even stronger nonclassical features when relative phase φ of the superposition is equal to the average photon number |α|^2. 相似文献
2.
In this paper, we introduce two new classes of nonlinear squeezed states that we name as f-deformed squeezed vacuum state|ξ, f even and f-deformed squeezed first excited state |ξ, f odd, which according to their production processes, essentially include only even and odd bases of Fock space, respectively. In the continuation, we introduce the superposition of these two distinct nonlinear squeezed states with a respective phase ?. Then, some of the criteria which imply the nonclassicality of the states, such as Mandel parameter, second-order correlation function, quadrature squeezing, amplitude-squared squeezing, Husimi and Wigner–Weyl quasi-distribution functions, are numerically examined. At last, by considering a well-known nonlinearity function associated with a nonlinear physical system, we present our results which outcome from the numerical calculations. It is shown that, the introduced f-deformed states can reveal high nonclassical features. 相似文献
3.
Entangled states based on two coherent states 3π/2 out of phase with each other, i.e. |α〉 and e^iФ|-iα〉, as well as on a special state with a relative phase Ф = |α|^2, are constructed. By analysing the amount of entanglement it is evident that entangled states based on this special state can be used as an excellent resource for quantum teleportation. It is also revealed that these entangled states possess some nonclassical features. 相似文献
4.
Amplitude-squared squeezing of the generalized odd-even coherent states of the anharmonic oscillator in a finite-dimensional Hilbert space 下载免费PDF全文
This paper discusses the properties of amplitude-squared squeezing of the generalized odd-even coherent states of anharmonic oscillator in finite-dimensional Hilbert space. It demonstrates that the generalized odd coherent states do exhibit strong amplitude-squared squeezing effects in comparison with the generalized even coherent states. 相似文献
5.
By analysing the action of a beamsplitter on squeezed vacuum states(SVSs),it is found that,if the two input light beams of the beamsplitter have the same squeezing amplitude and phase,the output state is a two-mode SVS,If the two input light beams of the beamsplitter have the same squeezing amplitude but a phase difference of π,the output state is a direct porduct state of two single-mode SVS.Based on these results,we propose to distill a maximally entangled SVS from a partially entangled SVS by using a 50/50 beamsplitter and photodetectors. 相似文献
6.
This paper presents a realistic scheme for the teleportation of coherent states in which a two-mode squeezed vacuum state serves as the quantum channel and the position-sum and momentum-difference of two local modes serve as the measuring observables. The average fidelity of the teleportation of coherent states is derived for finite squeezing parameters and it turns out that fidelity greater than 1/2 cannot be achieved by using a classical channel alone and the probability distribution of the measurement result is a Gaussian distribution around the unknown parameter of the input coherent state with a width given by the squeezing parameter. 相似文献
7.
It is shown that two trapped ions interacting with laser beams resonant to the first red side-band of center-of-mass mode,in Lamb-Dicke regime and under rotating wave approximation,is described by a Jaynes-Cummings model.For the initial condition that the motional state of center-of-mass mode is in vacuum state and the internal state is prepared in a coherent superposition of states,coherence and squeezing for the vibratile motion of center-of-mass mode are discussed,particularly,a“weak” coherent state and a “weak” squeezed vacuum state are obtained.Collapse and revival are also observed in this type of initial condition. 相似文献
8.
Interaction of a pair coherent state with a three-level Λ-type atom and generation of a modified Bessel-Gaussian state with a vortex structure 下载免费PDF全文
The evolution of a system state is derived based on the nonresonant interaction of a three-level "Λ" type atom with two cavity modes at a pair coherent state and two classic fields,and a cavity field state is analyzed in detail under conditional detecting.It is found that the quantized modified Bessel-Gaussian states as well as the superposition states consisting of the quantized vortex states with different weighted coefficients may be prepared through carefully preparing an initial atomic state and appropriately adjusting the interaction time.The scheme provides an additional choice to realize the two-mode quantized vortex state within the context of cavity quantum electrodynamics(QED). 相似文献
9.
An Intuitive Expression for Inseparability Condition of a Two-Mode Squeezed Vacuum State in a Thermal Environment 总被引:1,自引:0,他引:1 下载免费PDF全文
LIFu-Li LIHong-Rong 《中国物理快报》2004,21(6):991-994
Considering the propagation of a two-mode optical field that is initially in a squeezed vacuum state in a thermalenvironment, we obtain an intuitive expression for inseparability condition of the two-mode mixed state which isgiven in the coherent state representation. This condition shows that the two modes have quantum entanglementif and only if the coefficient of the correlation term between the two modes is larger than that of the off-diagonalterm of each mode in the density matrix. We find that even if the quantum channel is dynamically coupled to thethermal environment, the fidelity for teleporting coherent states larger than 1/2 is still the criterion for quantum teleportation. We also show that the entanglement, squeezing and quantum teleportation conditions are alwaysconsistent with each other. 相似文献
10.
We describe a scheme for the generation of macroscopic quantum-interference states for a collection of trapped ions by a single geometric phase operation. In the scheme the vibrational mode is displaced along a circle with the radius proportional to the number of ions in a certain ground electronic state. For a given interaction time, the vibrational mode returns to the original state, and the ionic system acquires a geometric phase proportional to the area of the circle, evolving from a coherent state to a superposition of two coherent states. The ions undergo no electronic transitions during the operation. Taking advantage of the inherent fault-tolerant feature of the geometric operation, our scheme is robust against decoherence. 相似文献
11.
相干态的叠加态的量子统计性质 总被引:5,自引:2,他引:3
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. 相似文献
12.
叠加激发相干态的量子特性 总被引:4,自引:0,他引:4
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. 相似文献
13.
Ran Zeng 《Optics Communications》2007,271(1):162-168
Nonclassical features of the superposition of two coherent states which are π/2 out of phase are discussed, such as sub-Poissonian photon statistics and quadrature squeezing, as well as negativity of the Wigner function. Special nonclassicality is found in the special state where the relative phase of superposition has relationship with the average photon number. The analysis of the amount of entanglement is also presented for the related two-mode entangled coherent states. 相似文献
14.
构造出了有限维Hilbert空间Roy型奇偶非线性相干态, 讨论了它们的正交归一完备性和振幅平方压缩效应. 研究表明, 在此空间中Roy型奇偶非线性相干态是归一完备的, 但不具有正交性; 当复参数相位角θ满足一定条件时它们存在振幅平方压缩效应, 同时导出了压缩条件与参数s,r以及函数f(n)之间的关系. 最后借助于数值计算, 发现对于5维(或7维)Hilbert空间中Roy型偶(或奇)非线性相干态, 当参数θ和Lamb-Dike参数η取某一给定值时, 在参数r变化的不同取值范围内, 它们均可以呈现振幅平方
关键词:
有限维Hilbert空间
Roy型非线性相干态
奇偶非线性相干态
振幅平方压缩 相似文献
15.
叠加多模薛定谔猫态纠缠光场的不等幂次高次差压缩 总被引:1,自引:1,他引:0
利用多模压缩态理论研究了由多模复共轭相干态、多模复共轭虚相干态和多模真空态的线性叠加所组成的三态叠加多模薛定谔猫态纠缠光场的广义非线性不等幂次高次差压缩特性.结果发现:①真空场对此猫态光场的不等幂次高次差压缩效应没有影响;②在一定条件下,此猫态光场的两个正交相位分量可分别呈现出不等幂次高次差压缩效应;③而在另外的条件下,此猫态光场的两个正交相位分量则可同时出现上述的不等幂次高次差压缩效应,这是一种与测不准关系相悖的现象,称此种现象为"双边差压缩"效应. 相似文献
16.
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. 相似文献
17.
18.
Syed Hamad Bukhari Muhammad Iqbal Hussain Salman Naeem Khan Muhammad Ashfaq Ahmad 《Optik》2012,123(24):2288-2291
Nonclassical features of Schrödinger cat state with two-mode superposition state based on two coherent states π out of phase by fixing the relative phase equal to average photon number are discussed. Study of two-mode quadrature squeezing, oscillatory and sub-Poissonian photon statistics show that nonclassicality exists for these states. However, it is observed that the considered states do not violates the Cauchy–Schwarz inequality. Furthermore, simultaneously existence of quadrature squeezing and sub-Poissonian photon statistics shows that these states have more nonclassical features than that of famous even and odd coherent states. 相似文献
19.
有限维希尔伯特空间q广义相干态振幅平方压缩 总被引:1,自引:0,他引:1
构造了有限维希尔伯特空间q变形非简谐振子广义相干态,研究了它的振幅平方压缩效应,结果表明,该量子态存在振幅平方压缩效应,并且给出了压缩条件与参数s,r,q之间的关系。 相似文献