Wigner functions and tomograms of the photon-depleted even and odd coherent states

Using the coherent state representation of Wigner operator and the technique of integration within an ordered product （IWOP） of operators, this paper derives the Wigner functions for the photon-depleted even and odd coherent states （PDEOCSs）. Moreover, in terms of the Wigner functions with respect to the complex parameter a the nonclassical properties of the PDEOCSs are discussed. The results show that the nonclassicality for the state ｜β, m〉o （or ｜β,m〉e） is more pronounced when m is even （or odd）. According to the marginal distributions of the Wigner functions, the physical meaning of the Wigner functions is given. Further, the tomograms of the PDEOCSs are calculated with the aid of newly introduced intermediate coordinate-momentum representation in quantum optics.

Continuous-variable quantum teleportation of even and odd coherent states through varied gain channels

This paper has investigated quantum teleportation of even and odd coherent states in terms of the EPR entanglement states for continuous variables. It discusses the relationship between the fidelity and the entanglement of EPR states, which is characterized by the degree of squeezing and the gain of classical channels. It shows that the quality of teleporting quantum states also depends on the characteristics of the states themselves. The properties of teleporting even and odd coherent states at different intensities are investigated. The difference of teleporting two such kinds of quantum states are analysed based on the quantum distance function.

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.

Even and Odd Coherent States for Time-Dependent Harmonic Oscillator

The dynamical invariant for a general time-dependent harmonic oscillator is constructed by making use of two linearly independent solutions to the classical equation of motion. In terms of this dynamical invariant we define the time-dependent creation and annihilation operators and relevantly introduce even and odd coherent states for time dependent harmonic oscillator. The mathematical and quantum statistical properties of these states are discussed in detail. The harmonic oscillator with periodically varying frequency is treated as a demonstration of our general approach.

Quasiprobability distributions of new kinds of even and odd nonlinear coherent states

Using a numerical computational method, quasiprobability distributions of new kinds of even and odd nonlinear coherent states （EONLCS） are investigated. The results show that the distributions of the new even nonlinear coherent states （NLCS） are distinct from those of the new odd NLCS and imply that the new EONLCS always exhibit some different nonclassical effects. Finally, with the aid of newly introduced intermediate coordinate-momentum representation in quantum optics, the tomograms of the new EONLCS are calculated. This is a new way of obtaining the tomogram function.

Finite-dimensional even and odd nonlinear pair coherent states and their some nonclassical properties

In this paper a new class of finite-dimensional even and odd nonlinear pair coherent states （EONLPCSs）, which can be realized via operating the superposed evolution operators D±（τ） on the state ｜q, 0）, is constructed, then their orthonormalized property, completeness relations and some nonclassical properties are discussed. It is shown that the finite-dimensional EONLPCSs possess normalization and completeness relations. Moreover, the finite-dimensional EONLPCSs exhibit remarkably different sub-Poissonian distributions and phase probability distributions for different values of parameters q, η and ξ.

Properties of Phase and Their Evolutions in Damped Odd and Even Coherent States

The properties of measured phase operators in damped odd and even coherent states have been studied. The fluctuations associated with measured phase and their squeezing in these states are investigated. The phase properties in damped superposition coherent states are considered too with the help of measured phase operators. These fluctuations and their squeezing are affected by damping and evolve with time elapsing.

Amplitude-squared squeezing of the generalized odd-even coherent states of the anharmonic oscillator in a finite-dimensional Hilbert space

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.

Superposition Coherent States and Their Properties

Special kinds of generalized superposition states, superposition coherent states, are studied in this paper. These states can be produced by superposing a pair of coherent states ｜ α 〉 and ｜- α 〉. Their quantum statistical properties, the fluctuations of field and squeezing have been discussed in detail. These properties are dependent on superposition phase. We also describe the squeezing regions in phase space for these states.

Dynamics of Nonclassicality of Time-and Conductivity-Dependent Squeezed States and Excited Even/Odd Coherent States

Recently, the quantum description of electromagnetic waves in conducting media has been performed. It has been demonstrated that in particular case, the Hamiltonian of the corresponding field can be expressed by Caldirola–Kanai Hamiltonian. In this paper, using the associated annihilation and creation operators of the above-mentioned quantized field, the time-and conductivity-dependent squeezed vacuum and one-photon squeezed states as well as their superpositions, and also the time-and conductivity-dependent excited even and odd coherent states are produced. Also,using a few well-known nonclassicality criteria, the time evolution of nonclassicality features of the above classes of obtained states, in addition to the influence of medium conductivity on them are demonstrated, numerically. It has been shown that the nonclassicality indicators may be adjusted by tuning the conductivity of media.

kth-order antibunching effect for a new kind of excited even and odd q-coherent states

A new kind of excited even q-coherent states （aq^-1）^m｜α〉q^e and excited odd q-coherent states （aq^-1）^m｜α〉q^o is constructed by acting with inverse boson operators on the even and odd q-coherent states. The m dependence of the kth-order antibunching effect is numerically studied for k = 2, 3, 4, 5. It is shown that the kth-order antibunching effect enhances as m increases. The larger k, the quicker the antibunching effect enhances.

奇偶相干态信号场下的量子关联和纠缠

为了实现两原子之间的非经典关联,借助于电磁诱导光透明(electromagnetically induced optical transparency,EIT)机制,利用量子态的映射技术,研究原子系综内两原子的量子关联和纠缠。结果表明:分别通过测量扰动刻画的量子关联和并发度刻画的量子纠缠,发现它们都能够被绝热地生成,但是,随着平均光子数的增加,二者的演变完全不同。随着平均光子数的增加,无论信号场是奇数相干态还是偶数相干态,它们都有利于量子关联的生成。对于奇相干态信号场,量子纠缠随着光子数的增加而逐渐减小;对于偶相干态信号场,量子纠缠却经历了一个先增加后减小的过程。系综内原子个数的增加,使得原子间的退相干加剧,从而导致量子关联和纠缠都被削弱。

两不同奇相干态组成的第Ⅲ种四态叠加多模叠加态光场的等阶N次方Y压缩

根据量子力学中的线性叠加原理，构造了由多模奇相干态与多模复共轭奇相干态这两种不同的奇相干态的线性叠加所组成的第Ⅰ种四态叠加多模叠加态光场｜Ψ(4)o，I〉q，利用多模压缩态理论，研究了态｜Ψ(4)o，I〉q的等阶N次方Y压缩特性.结果发现：1)当压缩阶数N为偶数时，在不同的条件下，态｜Ψ(4)o，I〉q可分别呈现三种状态：a)态｜Ψ(4)o，I〉q可处于等阶N-Y最小测不准态；b)态｜Ψ(4)o,I〉q的第一正交分量可呈现等阶N次方Y压缩效应；c)态｜Ψ(4)o，I〉q可呈现“半相干态”效应.2)当压缩阶数为奇数时，若果r1＝r2＝r，则在不同的条件下，态｜Ψ(4)o，I〉q可分别呈现三种状态：a)态｜Ψ(4)o，I〉q可处于等阶N-Y最小测不准态；b)态｜Ψ(4)o，I〉q的第一正交分量可呈现等阶N次方Y压缩效应；c)态｜Ψ(4)o，I〉q的第二正交分量可呈现等阶N次方Y压缩效应.3)“半相干态”是指在一定条件下，态｜Ψ(4)o，I〉q的两个正交分量其中一个正交分量处于等阶N-Y最小测不准态，另一个正交分量既不处于等阶N-Y最小测不准态也不呈现等阶N次方Y压缩效应.

两不同奇相干态组成的第种四态叠加多模叠加态光场的等阶N次方Y压缩

根据量子力学中的线性叠加原理 ,构造了由多模奇相干态与多模复共轭奇相干态这两种不同的奇相干态的线性叠加所组成的第 种四态叠加多模叠加态光场 |Ψ( 4 )o ,I〉q,利用多模压缩态理论 ,研究了态 | Ψ( 4 )o ,I〉q的等阶 N次方 Y压缩特性 .结果发现 :1 )当压缩阶数 N为偶数时 ,在不同的条件下 ,态 | Ψ( 4 )o ,I〉q 可分别呈现三种状态 :a)态 | Ψ( 4 )o ,I〉q可处于等阶 N- Y最小测不准态 ;b)态 | Ψ( 4 )o ,I〉q的第一正交分量可呈现等阶 N次方 Y压缩效应 ;c)态 | Ψ( 4 )o ,I〉q可呈现“半相干态”效应 .2 )当压缩阶数为奇数时 ,若果 r1=r2 =r,则在不同的条件下 ,态 |Ψ( 4 )o ,I〉q可分别呈现三种状态 :a)态 |Ψ( 4 )o ,I〉q可处于等阶 N - Y最小测不准态 ;b)态 |Ψ( 4 )o ,I〉q的第一正交分量可呈现等阶 N次方 Y压缩效应 ;c)态 | Ψ( 4 )o ,I〉q的第二正交分量可呈现等阶 N次方 Y压缩效应 .3)“半相干态”是指在一定条件下 ,态 | Ψ( 4 )o ,I〉q的两个正交分量其中一个正交分量处于等阶N- Y最小测不准态 ,另一个正交分量既不处于等阶 N- Y最小测不准态也不呈现等阶 N次方

多模奇相干态光场中的N-Y最小测不准态与N-H最小测不准态

本文根据新近建立的多模辐射场的广义非线性等阶高阶压缩理论，对多模奇相干态光场｜Ψ，ｏ〉ｑ中的Ｎ次方Ｙ压缩、Ｎ次方Ｈ压缩、Ｎ－Ｙ最小测不准态以及Ｎ－Ｈ最小测不准态等进行了详细研究．结果表明：１）当压缩阶数Ｎ为偶数时，多模奇相干态｜Ψ，ｏ〉ｑ总是恒处于Ｎ－Ｙ最小测不准态；当Ｎ为奇数时，态｜Ψ，ｏ〉ｑ既不处于Ｎ－Ｙ最小测不准态，也不呈现Ｎ次方Ｙ压缩效应．２）当ｑ·Ｎ为偶数时，多模奇相干态｜Ψ，ｏ〉ｑ总是恒处于Ｎ－Ｈ最小测不准态；当ｑ·Ｎ为奇数时，态｜Ψ，ｏ〉ｑ既不处于Ｎ－Ｈ最小测不准态，也不呈现Ｎ次方Ｈ压缩效应．３）多模奇相干态｜Ψ，ｏ〉ｑ恒处于Ｎ－Ｙ最小测不准态与恒处于Ｎ－Ｈ最小测不准态的条件明显不同。

一种新型的多模虚奇相干态光场的两种等阶最小测不准态——等阶N-Y与等阶N-H最小测不准态

本文利用新近建立的多模压缩态理论 ,详细研究了一种新型的多模虚奇相干态光场|Ψ( 2 )i,o〉q的广义非线性等阶高阶压缩特性 .结果发现 :1 )当压缩阶数 N为偶数时 ,多模虚奇相干态 |Ψ( 2 )i,o〉q总是恒处于等阶 N-Y最小测不准态 ;而当 N为奇数时 ,态 |Ψ( 2 )i,o〉q既不处于等阶 N-Y最小测不准态 ,也不呈现等阶 N次方 Y压缩效应 .2 )当腔模总数 q与压缩阶数 N这两者之积 q·N为偶数时 ,多模虚奇相干态 | Ψ( 2 )i,o〉q 始终恒处于等阶 N-H最小测不准态 ;而当q·N为奇数时 ,态 | Ψ( 2 )i,o〉q 既不处于等阶 N-H最小测不准态 ,也不呈现等阶 N次方 H压缩效应 .3 )上述的等阶 N -Y最小测不准态与等阶 N-H最小测不准态属于两种截然不同的等阶最小测不准态 ,两者无论在定义上、性质上、条件上还是在产生机制上都存在着严格的本质区别 .4)多模虚奇相干态光场 | Ψ( 2 )i,o〉q与已报道的多模奇相干态光场 | Ψ,o〉q 和多模复共轭奇相干态光场 | Ψ( 2 )* ,o〉q等虽是三种不同的量子光场态 ,但却具有完全相同的量子统计性质 ;即在相同条件下它们都恒处于上述的两种等阶最小测不准态 ,但始终不呈现等阶 N次方 Y压缩与等阶 N次方 H压缩效应 .

两不同奇相干态组成的第Ⅲ种四态叠加多模叠加态光场的等阶N次方H压缩

本文构造了由两不同奇相干态组成的第 种四态叠加多模叠加态光场 |ψ(4 )o , 〉q.利用新近建立的多模压缩态理论 ,详细研究了态 |ψ(4 )o , 〉q的广义非线性等阶 N次方 H压缩特性 ,结果发现由多模奇相干态 |ψ,o〉q和多模虚奇相干态 |ψ(2 )i ,o〉q这两者线性叠加所组成的新量子光场态、|ψ(4 )o , 〉q是一种典型的非经典光场 .1 )当腔模总数 q与压缩阶数 N的乘积 q·N为偶数、且 q N=4m( m=1 ,2 ,3 ,… ,… )时 ,态 |ψ(4 )o , 〉q恒处于等阶 N-H最小测不准态 ,与其它参量的取值无关 ;2 )当 q N为偶数、且 q N=4m-2 ( m=1 ,2 ,3 ,… ,… )时 ,( i)态 |ψ(4 )o , 〉q可呈现等阶 N次方 H压缩效应 ,其两正交分量的压缩特性呈现周期性变化的、互补对称关系 ;( ii)态 |ψ(4 )o , 〉q可呈现“半相干态”效应 .3 )当 q N为奇数时 ,态 |ψ(4 )o , 〉q始终不呈现等阶N次方 H压缩效应 ,也不处于等阶 N-H最小测不准态 ,但在一定条件下可呈现“半相干态”效应 .

多模复共轭奇、偶相干态光场的N次方Y压缩与N次方H压缩

利用新近提出的多模辐射场的广义非线性等阶高阶压缩理论，对多模复共轭奇、偶相干态光场的Ｎ次方Ｙ压缩与Ｎ次方Ｈ压缩特性进行了详细研究．结果发现：①多模复共轭奇相干态光场，压缩阶数Ｎ为偶数时，只存在Ｎ－Ｙ最小测不准态；而当腔模总数ｑ与压缩阶数的乘积ｑ·Ｎ为偶数时，只存在Ｎ－Ｈ最小测不准态；此外，无论Ｎ及ｑ·Ｎ为何值，不呈现Ｎ次方Ｙ压缩与Ｎ次方Ｈ压缩效应．②多模复共轭偶相干态光场在一定条件下可呈现出周期性变化的任意阶的Ｎ次方Ｙ压缩与Ｎ次方Ｈ压缩效应．③多模偶相干态光场与多模复共轭偶相干态光场两者的压缩效果和压缩特性完全相同，这种现象称为“压缩简并”

四态叠加多模光场的等幂次N次方H压缩

根据量子力学中的线性叠加原理 ,构造了由奇、偶相干态光场所组成的一种新型的四态叠加多模叠加态光场 |Ψ( 4 )o ,eⅢ〉q.它是由多模虚奇相干态和多模虚偶相干态这两者的线性叠加所组成的 利用多模压缩态理论详细研究了态 |Ψ( 4 )o ,eⅢ〉q 的等幂次N次方H压缩特性 结果发现 :当腔模总数 q与压缩次数N的乘积为奇数时 ,若各模初始相位和 qj=1φj、态间叠加几率幅γo、γe 以及态间相位差θe-θo 等相关参量满足一定的不同条件时 ,态 |Ψ( 4 )o,eⅢ〉q 可分别呈现以下非经典效应 :i)等幂次N次方H压缩 ;ii)“半相干态”

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。