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Algebraic and group treatments to nonlinear displaced number states and their nonclassicality features:A new approach

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Chinese Physics B 2015年第6期24卷 334-340页

作者： N Asili Firouzabadi m k.tavassoly m J Faghihi Atomic and molecular Group Faculty of PhysicsYazd University The Laboratory of Quantum Information Processing Yazd University Physics and Photonics Department Graduate University of Advanced Technology

Recently, nonlinear displaced number states （NDNSs） have been manually introduced, in which the deformation function f（n） has been artificially added to the previously well-known displaced number states （DNSs）. Indeed, just a simple comparison has been performed between the standard coherent state and nonlinear coherent state for the formation of NDNSs. In the present paper, after expressing enough physical motivation of our procedure, four distinct classes of NDNSs are presented by applying algebraic and group treatments. To achieve this purpose, by considering the DNSs and recalling the nonlinear coherent states formalism, the NDNSs are logically defined through an algebraic consideration. In addition, by using a particular class of Gilmore-Perelomov-type of SU（1,1） and a class of SU（2） coherent states, the NDNSs are introduced via group-theoretical approach. Then, in order to examine the nonclassical behavior of these states, sub-Poissonian statistics by evaluating mandel parameter and Wigner quasi-probability distribution function associated with the obtained NDNSs are discussed, in detail.

关键词： displaced number state nonlinear coherent state Wigner function nonclassical state

The performance of a dissipative electrooptomechanical system using the Caldirola–kanai Hamiltonian approach

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Communications in Theoretical Physics 2023年第7期75卷 123-131页

作者： m m Atabaki m k.tavassoly A Behjat m Hassani Nadiki k Javidan Optics and Laser Group Faculty of PhysicsYazd UniversityYazdIran Department of Physics School of SciencesFerdowsi University of MashhadMashhad 91775-1436Iran

By combining all optical,electronic,and mechanical capabilities,electro-optomechanical systems,along with the use of mechanical displacement,the conversion of low-frequency electrical signals into much higher-frequency optical signals is *** process provides several capabilities that have very important applications in various fields,including classical,as well as quantum *** this regard,the inevitable effect of dissipation on the performance indicators of such systems is one of the important issues affecting its *** approach for investigating the effect of dissipation is based on a time-dependent Hamiltonian has been known as the Caldirola-kanai(Ck)Hamiltonian,wherein the exponentially increasing mass,i.e.m(t)=m0(eγt)enters the mechanical oscillator *** this approach shows that,the performance of the system under the influence of dissipation with Ck Hamiltonian formalism,in which the dissipation terms are embedded in the Hamiltonian,are more logical,analytical,and reliable than considering the effect of dissipation with the phenomenological method(including the dissipation effects in the equations of motion by hand),which has been recently used in Bagci et al.(Nature,507,81,2014).In our method,it is also possible to monitor the performance of the system via the adjustment of dissipation components,i.e.,resistance R and reactance L(and Ck damping parameterγ)in the electrical(mechanical membrane)part of the system.

关键词： dissipative system electro-optomechanical system Caldirola-kanai Hamiltonian

Entanglement and Other Nonclassical Properties of Two Two-Level Atoms Interacting with a Two-mode Binomial Field: Constant and Intensity-Dependent Coupling Regimes

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Communications in Theoretical Physics 2015年第10期64卷 439-446页

作者： m.k.tavassoly H.Hekmatara Atomic and molecular Group Faculty of Physics Yazd University Photonic Research Group Engineering Research Center Yazd University The Laboratory of Quantum Information Processing Yazd University

In this paper, we consider the interaction between two two-level atoms and a two-mode binomial field with a general intensity-dependent coupling regime. The outlined dynamical problem has explicit analytical solution, by which we can evaluate a few of its physical features of interest. To achieve the purpose of the paper, after choosing a particular nonlinearity function, we investigate the quantum statistics, atomic population inversion and at last the linear entropy of the atom-field system which is a good measure for the degree of entanglement. In detail, the effects of binomial field parameters, in addition to different initial atomic states on the temporal behavior of the mentioned quantities have been analyzed. The results show that, the values of binomial field parameters and the initial state of the two atoms influence on the nonclassical effects in the obtained states through which one can tune the nonclassicality criteria *** intensity-dependent coupling function equal to 1 reduces the results to the constant coupling case. By comparing the latter case with the nonlinear regime, we will observe that the nonlinearity disappears the pattern of collapse-revival phenomenon in the evolution of mandel parameter and population inversion(which can be seen in the linear case with constant coupling), however, more typical collapse-revivals will be appeared for the cross-correlation function in the nonlinear case. Finally, in both linear and nonlinear regime, the entropy remains less than(but close to) 0.5. In other words the particular chosen nonlinearity does not critically affect on the entropy of the system.

关键词： Jaynes–Cummings model atom-field interaction two-m

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

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Communications in Theoretical Physics 2017年第4期67卷 365-376页

作者： R.Daneshmand m.k.tavassoly Atomic and molecular Group Faculty of PhysicsYazd UniversityYazdIran Photonics Research Group Engineering Research CenterYazd UniversityYazdIran The Laboratory of Quantum Information Processing Yazd UniversityYazdIran

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.

关键词： Caldirola–kanai Hamiltonian squeezed vacuum state one-photon squeezed state excited even coherent state excited odd coherent state

Nonlinear Quantum Optical Springs and Their Nonclassical Properties

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Communications in Theoretical Physics 2011年第8期56卷 327-332页

作者： m.J.Faghihi m.k.tavassoly Atomic and molecular Group Faculty of PhysicsYazd University

光春天在泛音振荡器的 Hamiltonian 从摆动的频率的量子化的要求产生的量的原来的想法。这个目的被考虑常数的春天达到(并且那么它的频率) 取决于另一个系统的量状态。最近，这被认识到由频率调整的假设到提及的想法能被建立。在现在的... 详细信息

光春天在泛音振荡器的 Hamiltonian 从摆动的频率的量子化的要求产生的量的原来的想法。这个目的被考虑常数的春天达到(并且那么它的频率) 取决于另一个系统的量状态。最近，这被认识到由频率调整的假设到提及的想法能被建立。在现在的纸，我们概括量的途径有到到自然地处于非线性的协调状态，我们从到达一个物理系统观察的放射地的紧张的频率的依赖的特别注意的光春天被我们作为非线性的量叫了光春天。然后，在非线性的量的概括 Hamiltonian 的介绍以后，光春天和它是答案，我们将调查获得的状态的 nonclassical 性质。特殊，在分发的典型倒塌和苏醒工作并且作为特别的量特征，压榨的参数将被揭示。

关键词：非线性相干态量子光学非经典特性振荡频率物理系统广义非线性挤压参数分布函数

Spontaneous Emission Originating from Atomic BEC Interacting with a Single-mode Quantized Field

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Communications in Theoretical Physics 2018年第6期69卷 711-721页

作者： E.Ghasemian m.k.tavassoly Atomic and molecular Group Faculty of Physics Yazd University

In this paper we present a general theoretical model for the interaction between a number of two-level atoms constituting Bose-Einstein condensate(BEC) and a single-mode quantized field. In addition to the usual interacting terms, we take into account interatom as well as higher-order atom-field interactions. To simplify the Hamiltonian o system, after using the Bogoliubov approximation we proceed to calculate the transformed operators of atoms and field Then, to quantify the spontaneous emission, we get analytical expressions for the expectation value ofJ?z as the atomic population inversion(API), in the cases of number and coherent states for the atomic subsystem. Our results show that the above-mentioned model interaction leads to the appearance of collapse-revival phenomenon in API. In more detail the revival time may be tuned by adjusting the interatom interaction constant. Also, the damping process lowers the amplitude of API, but does not change the CR times for weak damping. moreover, increasing the damping may decrease the number of CRs in a given interval of time such that no revival occurs. Briefly, it may be concluded that in the resonant case the revival times are insensitive to the change of the higher-order atom-field interaction constant and are affected only by the interatom interactions. Finally, we express that, how we can find a practical procedure to measure the quantum states of atoms in BEC.

关键词：量子化原子 Hamiltonian 交往排放 BEC 相互作用发源

Production of the Superposition of Nonlinear Coherent States and Entangled Nonlinear Coherent States

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Communications in Theoretical Physics 2015年第9期64卷 341-344页

作者： A.karimi m.k.tavassoly Atomic and molecular Group Faculty of Physics Yazd University Physics Group Islamic Azad University of Abadeh The Laboratory of Quantum Information Processing Yazd University

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.

关键词： superposition entangled nonlinear coherent states

Quantum phase distribution and the number-phase Wigner function of the generalized squeezed vacuum states associated with solvable quantum systems

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Chinese Physics B 2012年第5期21卷 265-273页

作者： G.R.Honarasa m.k.tavassoly m.Hatami Department of Physics Faculty of ScienceShiraz University of Technology Atomic and molecular Group Faculty of PhysicsYazd University

The quantum phase properties of the generalized squeezed vacuum states associated with solvable quantum systems are studied by using the Pegg-Barnett ***,two nonclassical features,i.e.,squeezing in the number and phase operators,as well as the number-phase Wigner function of the generalized squeezed states are *** to some actual physical situations,the present approach is applied to two classes of generalized squeezed states：solvable quantum systems with discrete spectra and nonlinear squeezed states with particular nonlinear ***,the time evolution of the nonclassical properties of the considered systems has been numerically investigated.

关键词： squeezed vacuum states solvable quantum systems phase distribution number phaseWigner function

Representations of coherent and squeezed states in an extended two-parameter Fock space

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Chinese Physics C 2012年第8期36卷 703-709页

作者： m. k. tavassoly m. H. Lake Atomic and molecular Group Faculty of Physics Yazd University Yazd Iran Photonics Research Group Engineering Research Center Yazd University Yazd Iran

Recently an f -deformed Fock space which is spanned by ｜ n λ was introduced. These bases are the eigenstates of a deformed non-Hermitian Hamiltonian. In this contribution, we will use rather new nonorthogonal basis vectors for the construction of coherent and squeezed states, which in special case lead to the earlier known states. For this purpose, we first generalize the previously introduced Fock space spanned by ｜ n λ bases, to a new one, spanned by extended two-parameters bases ｜ n λ 1 ,λ 2 . These bases are now the eigenstates of a non-Hermitian Hamiltonian H λ 1 ,λ 2 = a λ 1 ,λ 2 a ＋ 1 2 , where a λ 1 ,λ 2 = a ＋ λ 1 a ＋ λ 2 and a are, respectively, the deformed creation and ordinary bosonic annihilation operators. The bases ｜ n λ 1 ,λ 2 are nonorthogonal （squeezed states）, but normalizable. Then, we deduce the new representations of coherent and squeezed states in our two-parameter Fock space. Finally, we discuss the quantum statistical properties, as well as the non-classical properties of the obtained states numerically.

关键词： coherent state squeezed state representation theory quantum statistics non-orthogonal bases