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

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Chinese Physics B 2008年第4期17卷 1254-1262页

作者：王继锁孟祥国 Department of Physics Liaocheng University

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.

关键词： photon-depleted even and odd coherent state Wigner function intermediate coordinate-momentum representation tomogram

New Approach for Calculating tomograms of Quantum States by Virtue of the IWOP Technique

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Communications in Theoretical Physics 2007年第3期47卷 431-436页

作者： FAN Hong-Yi WANG Ji-Suo Department of Physics Shanghai Jiao Tong University Shanghai 200030 China Department of Material Science and Engineering University of Science and Technology of China Hefei 230026 China Department of Physics Liaocheng University Liaocheng 252059 China

We show that for tomographic approach there exist two mutual conjugate quantum states [p,σ, τ） and [x,μ, ν）（named the intermediate coordinate-momentum representation）, and the two Radon transforms of the Wigner operator are just the pure-state density matrices [p）σ1τσ1τ （p｜ and （p）λ,ν,λ,ν,（x｜ respectively. As a result, the tomogram of quantum states can be considered as the module-square of the states＇ wave function in these two representations. Throughout the paper we fully employ the technique of integration within an ordered product of operators. In this way we establish a new convenient formalism of quantum tomogram.

关键词： tomogram intermediate coordinate-momentum representation

Generalized photon-added coherent state and its quantum statistical properties

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Chinese Physics B 2010年第10期19卷 296-304页

作者：袁洪春徐学翔范洪义 Department of Physics Shanghai Jiao Tong University College of Physics and Communication Electronics Jiangxi Normal University

In this paper, we propose a class of the generalized photon-added coherent states （GPACSs） obtained by repeatedly operating the combination of Bosonie creation and annihilation operatoes on the coherent state. The normalization factor of GPACS is related to Hermite polynomial. We also derive the explicit expressions of its statistical properties such as photocount distribution, Wigner function and tomogram and investigate their behaviour as the photon-added number varies graphically. It is found that GPACS is a kind of nonclassical state since Wigner function exhibits the negativity by increasing the photon-added number.

关键词： generalized photon-added coherent state photocount distribution Wigner function tomogram

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

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Chinese Physics B 2009年第6期18卷 2300-2306页

作者：孟祥国王继锁梁宝龙 Department of Physics Liaocheng University

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.

关键词： even and odd nonlinear coherent state Wigner W-function Husimi Q-function tomogram

Decoherence of photon-subtracted squeezed vacuum state in dissipative channel

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Chinese Physics B 2011年第2期20卷 239-246页

作者：徐学翔袁洪春范洪义 College of Physics and Communication Electronics Jiangxi Normal University Department of Physics Shanghai Jiao Tong University

This paper investigates the decoherence of photo-subtracted squeezed vacuum state （PSSVS） in dissipative channel by describing its statistical properties with time evolution such as Wigner function, Husimi function, and tomogram. It first calculates the normalization factor of PSSVS related to Legendre polynomial. After deriving the normally ordered density Operator of PSSVS in dissipative channel, one obtains the explicit analytical expressions of time evolution of PSSVS＇s statistical distribution function. It finds that these statistical distributions loss their non-Gaussian nature and become Gaussian at last in the dissipative environment as expected.

关键词： photon-subtracted squeezed vacuum state Wigner function Husimi function tomogram

Wigner function for the generalized excited pair coherent state

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Chinese Physics B 2008年第5期17卷 1791-1797页

作者：孟祥国王继锁梁宝龙李洪奇 Department of Physics Liaocheng University Department of Physics Heze University

This paper introduces the generalized excited pair coherent state （GEPCS）. Using the entangled state 〈η〉 representation of Wigner operator, it obtains the Wigner function for the GEPCS. In the ρ-γ phase space, the variations of the Wigner function distributions with the parameters q, α, k and l are discussed. The tomogram of the GEPCS is calculated with the help of the Radon transform between the Wigner operator and the projection operator of the entangled state ｜η1, η2, τ1, τ2｜. The entangled states ｜η〉 and ｜η1, η2, τ1, τ2〉 provide two good representative space for studying the Wigner functions and tomograms of various two-mode correlated quantum states.

关键词： generalized excited pair coherent state Wigner function tomogram entangled state representation

Entanglement Involved in Pair Coherent State Studied via Wigner Function Formalism

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Communications in Theoretical Physics 2009年第12期52卷 1071-1075页

作者： HU Li-Yun~(1,2)and FAN Hong-Yi~21 College of Physics and Communication Electronics, Jiangxi Normal University, Nanchang 330022, China2 Department of Physics, Shanghai Jiao Tong University, Shanghai 200030, China College of Physics and Communication Electronics Jiangxi Normal University Nanchang 330022 China Department of Physics Shanghai Jiao Tong University Shanghai 200030 China

We calculate Wigner function,tomogram of the pair coherent state by using its Schmidt decompositionin the coherent state *** turns out that the Wigner function can be seen as the quantum entanglement(QE)between two two-variable Hermite polynomials(TVHP)and the tomogram is further simplified as QE of twosingle-variable Hermite *** Husimi function of pair coherent state is also calculated.

关键词： pair coherent state Wigner function tomogram Husimi function

Variation of Electromagnetic Tornogram Before and After Earthquakes

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Earthquake Research in China 1998年第2期12卷 70-76页

作者： Sun Cichang,Wang Xusheng,Liu Qingfang,Tao Yulu,Yu Ping,and Feng RuiInstitute of Geophysics,SSB,Beijing 100081,China Department of Geophysics,Peking University,Beijing 100871,China Seismnlogical Bureau of Hunan Province,Changsha 410001,China Center for Seismological Data and Information,SSB,Beijing 100045,China

Cross-well electromagnetic tomography has been used to monitor the changes of the abso rption coefficient of electromagnetic waves before and after earthquakes for 5 years at Dahuichang fault since *** has been found that 3 months before the occurrence of moderately strong earthquakes(ML≥4.0,△tomogram appeared as follows:The mean-value of the absorption coefficient dropped about 10% compared with the annually decreasing tendency; the mean difference of pixels suddenly decreased or increased in different directions; and the entropy of the paragenic matrix in a tomogram decreased and the number of low absorption pixels *** is inferred that such changes in electromagnetic tomograms are attributed to the variation of micro-cracks and porosity in *** tomography can be studied as a new technique to detect earthquake precursors.

关键词： Electromagnetic tomogram Dahuichang fault Earthquake precursor Imageanalysis.