Entanglement and Pancharatnam Phase of a Four-Level Atom in Coherent States Within Generalized Heisenberg Algebra

We consider a four-level atom (FLA) interacting with a field mode that is initially in a coherent state associated with a generalized Heisenberg algebra (CSGHA). The dynamical behavior of quantum entropy, the Pancharatnam phase, and the Mandel parameter are investigated. The statistical and nonclassical properties of the field in regard to its CSGHA are discussed through the evolution of the Mandel parameter, and the effects of the initial atomic state position and time-dependent coupling given in terms of atomic speed and acceleration are examined. The results show that the CSGHA strength and time-dependent coupling based on the atomic speed and acceleration have the potential to affect the time evolution of the entanglement, the Pancharatnam phase, and the Mandel parameter.     

Quantum Key Distribution Based on Coherent States

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R-Deformed Heisenberg Algebra, Quantum Mechanics, and Virasoro Algebra

We review the R-deformed Heisenberg algebra and its Fock space representation.We construct the R-deformed quantum mechanics in N dimensions, and proposea new R-deformed Virasoro algebra.     

Quantum Superdense Coding Based on Coherent States in Cavity QED

A physical scheme for the implementation of quantum superdense coding has been proposed in Cavity QED. The detuned interaction between Λ-type three-level atoms and coherent fields constitute the main superdense coding process. The quantum superdense coding can be realized in an easier way, and the atoms are not excited during the whole process, so the effect of atomic decay is eliminated naturally.     

Classical and Quantum Coherent States

p-Mechanics is a consistent physical theory which describes both quantum and classical mechanics simultaneously (V. V. Kisil, p-Mechanics as a physical theory. An Introduction, E-print:arXiv:quant-ph/0212101, 2002; International Journal of Theoretical Physics 41(1), 63–77, 2002). We continue the development of p-mechanics by introducing the concept of states. The set of coherent states we introduce allows us to evaluate classical observables at any point of phase space and simultaneously to evaluate quantum probability amplitudes. The example of the forced harmonic oscillator is used to demonstrate these concepts.     

The qs-Hermite Polynomial and the Representations of Heisenberg and Quantum Heisenberg Algebra

By introducing a pair of canonical conjugate two-parameter deformed operators D_qs, X_qs,we can naturally obtain the form of qs-analogous Taylor series for an arbitrary analytic function, and explicitly construct the realizations of Heisenberg and two-parameter deformed quantum Heisenberg algebra by means of the operators D_qs and X_qs, and it is shown that the qs-analogous Hermite polynomials are the representations of Heisenberg and the quantum Heisen berg algebra.     

Physical Properties,Field Purity,and Quantum Phase for a Two-Level Atom in Photon-Added Coherent States for the Morse Potential

In this paper, we consider a two-level atom (TLA) interacting with a field mode, which is initially in the photon-added coherent state for the Morse potential (PACSMP). We investigate the dynamical behavior of quantum entropy, the geometric phase, and the Mandel parameter and discuss the statistical and nonclassical properties of the field with regards to its PACSMP through the evolution of the Mandel parameter. We examine the effects of the number of added photons, the initial-state setting, and the Morse-potential parameters. We establish the relationship between the field purity, nonclassical properties, and geometric phase of the system state during the time evolution. The results show that the numbers of added photons and CSMP strength have the potential to affect the time evolution of the field purity, the geometric phase, and the Mandel parameter. We explore some important physical phenomena such as sudden death and sudden birth of the nonlocal correlation between TLA and field systems.     

Quantum Discord and Entanglement of Quasi-Werner States Based on Bipartite Entangled Coherent States

Present work is an attempt to compare quantum discord and quantum entanglement of quasi-Werner states formed with the four bipartite entangled coherent states (ECS) used recently for quantum teleportation of a qubit encoded in superposed coherent state. Out of these, the quasi-Werner states based on maximally ECS due to its invariant nature under local operation is independent of measurement basis and mean photon numbers, while for quasi-Werner states based on non-maximally ECS, it depends upon measurement basis as well as on mean photon number. However, for large mean photon numbers since non-maximally ECS becomes almost maximally entangled therefore dependence of quantum discord for non-maximally ECS based quasi-Werner states on the measurement basis disappears.     

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.     

The Two-Variable Coherent States of the Quantum Algebra suq(l,1)

By means of the k-order q-boson realizations of su_q(1,1), a new kind of q-coherent states, the two-variable coherent states, are introduced for the quantum algebra su_q(l,1).They are relative to a definite irreducible representation of su_q(1,1) and shown to satisfy a completeness relation in a subspace of q-boson's Fock space. With the help of these coherent states the z-representation, representation in functional space, for su_q(1,1) is also discussed.     

Entanglement in Bipartite Generalized Coherent States

Entanglement of formation in a class of bipartite generalized coherent states is discussed. It is shown that a positive parameter can be associated with these bipartite states so that the states with equal value for the parameter are of equal entanglement. For the class of states considered, the maximum possible entanglement of one ebit is attained if the value of the positive parameter is . It is shown that the entanglement of formation is one ebit when the relative phase between the composing states is π in the class of bipartite generalized coherent states considered.     

Quantum Correlation Coefficients for Angular Coherent States

Quantum covariance and correlation coefficients of angular or SU（2） coherent states are directly calculated for all irreducible unitary representations. These results explicitly verify that the angular coherent states minimize the Robertson-Schrodinger uncertainty relation for all spins, which means that they are the so-called intelligent states. The same results can be obtained by the Schwinger representation approach.     

Quantum Discord in Optical Coherent States

We study the dynamics of quantum correlation of optical coherent-state qubits affected by the environment. It consists in sending these states via a decohering quantum channel. The states used as the support of the encoding information are affected by an amplitude damping channel. The quantum discord is one of type of quantum correlations between the qubits. The discord and its dynamics of two qubits in non-Markovian environments are evaluated.     

广义Kerr介质奇偶相干态中相位算符的压缩性质

利用S.M.Barbett和D.T.Pegg提出的测量相应算符，研究了存在广义Kerr介质时，奇偶相干态中测量相位的二阶和高阶压缩性质。着重讨论了广义Kerr介质的非线性阶数m对奇偶相干态中测量相位压缩的影响。结果表明：在广义Kerr奇偶相干态中，测量相位算符存在间歇性的偶数阶CS类压缩和双偶数阶CN类压缩，压缩的深度与非线性介质的阶数m、|α}^2及δ有关。     

Generalized Barut-Girardello Coherent States for Mixed States with Arbitrary Distribution

In the paper we examine some properties of the generalized coherent states of the Barut-Girardello kind. These states are defined as eigenstates of a generalized lowering operator and they are strongly dependent on the structure constants. Besides the pure coherent states we focused our attention on the mixed states one, which are characterized by different probability distributions. As some examples we consider the thermal canonical distribution and the Poisson distribution functions. We calculate for these cases the Husimi’s Q and quasi-probability P-distribution functions.     

Generalized Coherent States for Position-Dependent Effective Mass Systems

A generalized scheme for the construction of coherent states in the context of position-dependent effective mass systems has been presented. This formalism is based on the ladder operators and associated algebra of the system which are obtained using the concepts of supersymmetric quantum mechanics and the property of shape invariance. In order to exemplify the general results and to analyze the properties of the coherent states, several examples have been considered.     

Generalized Coherent States for Position-Dependent Effective Mass Systems

A generalized scheme for the construction of coherent states in the context of position-dependent effective mass systems has been presented. This formalism is based on the ladder operators and associated algebra of the system which are obtained using the concepts of supersymmetric quantum mechanics and the property of shape invariance. In order to exemplify the general results and to analyze the properties of the coherent states, several examples have been considered.     

Generalized Weyl Ordering and Nonlinear Coherent States

In the context of the nonlinear coherent state (NLCS) theory we introduce the generalized Weyl orderingoperator formulation. The corresponding generalized Wigner operator turns out to be the Weyl ordered Dirac δ-operatorfunctions. The completeness relation of NLCS is recast into generalized Weyl ordering form. The relationship betweennormal ordering, antinormal ordering and the generalized Weyl ordering is established which constitute a self-consistenttheory for NLCS.     

Generalized Weyl Ordering and Nonlinear Coherent States

In the context of the nonlinear coherent state(NLCS)theory we introduce the generalized weyl ordering operator formulation.The corresponding generalzied wigner operator turns out to be the Weyl ordered diracδ-operator functions.The completeness relation of NLCS is recast into generalized Weyl ordering form,The relationship between normal ordering,antinormal ordering and the generalized Weyl ordering is established which constitute a self-consistent theory for NLCS.