Morteza Soltani

University of Isfahan, Isfahan, Ostān-e Eşfahān, Iran

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Publications (19)30.45 Total impact

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    ABSTRACT: The dynamic behavior of the quantum discord in one-dimensional scattering of a qubit (a spin-1/2 particle) by single and double well-localized fixed spin impurities is investigated theoretically. It is assumed that the incident particle is scattered by the spin impurities through the Ising and/or Heisenberg interactions. These potentials create quantum mechanical correlation between the reflected and transmitted parts of the scattered system and the impurities. It is shown that the incident momentum, strength of the interaction potentials, and the separation between the impurities can be regarded as the control parameters for the quantum discord and concurrence manipulations. In particular, it has been found that the correlations are periodic functions of the wavelength of the incident particle when it is scattered by the double spin impurities.
    International Journal of Theoretical Physics 12/2014; 53(12). · 1.09 Impact Factor
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    ABSTRACT: Generation of quantum entanglement in scattering of particles from fixed localized spin impurities is investigated. In the suggested approach, the incident particle is described by a Gaussian wave packet with an initial definite width. It is also assumed that the incident particle interacts with the impurities through the Ising and/or Heisenberg interactions. It is shown that the created entanglement is strongly affected by the initial width of the incident wave packet. For an initially well localized wave packet the created entanglement is low. However, as the initial width increases the entanglement grows appreciably and for sufficiently large values of the initial width the present results tend to our previous results for scattering of plane waves from spin impurities. For scattering from a double spin impurity, it is shown that the periodic behavior of the previous results changes significantly.
    03/2014; 68(4).
  • Morteza Soltani, Saba Sayyahi
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    ABSTRACT: In this work the Hawking-Unruh effect on the quantum entanglement of bosonic field in background of a spherically symmetric black hole of Gauss-Bonnet gravity is investigated beyond the single mode approximation. The entanglement decreases due to Hawking-Unruh effect. However, it has been shown that the dimensions of space time, Gauss-Bonnet term and the parameter β of initial entangled state would be influenced on this degradation. In our investigation, we consider the accelerated observer either near or far from the event horizon and inspect entanglement degradation for them. The mutual information of this bosonic system is also calculated in beyond the single mode approximation and we show that the mutual information will have different behavior when the Hawking temperature increases.
    International Journal of Theoretical Physics 01/2014; · 1.09 Impact Factor
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    ABSTRACT: In this paper,we introduce a system containing of two qubits interacting with a cavity which interacted with a reservoir. Using the Fano technique we will show this system is equivalent with two qubits which are interacting with a common heat bath. We also add a laser field and the behavior of this system is investigated when the qubits are dissipative. In this way we show that the presence of laser field can generate a high entanglement in this system, in other word the pump of energy using the laser field can compensate for the lose of dissipation of qubits. We also show that our system is almost insensible to temperature.
    The European Physical Journal D 12/2013; 67(12):256-. · 1.51 Impact Factor
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    Saeed Pegahan, Morteza Soltani, F. Kheirandish
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    ABSTRACT: The entanglement generation in a two-qubit system interacting with electromagnetic vacuum field and an external local magnetic field is investigated in the framework of the master equation. The time-evolution for the most general density matrix of the two-qubit system is obtained and solved. It is shown that the two-qubit system ends up in an entangled stationary state independent on the initial separable state.
    International Journal of Theoretical Physics 12/2013; 52(12). · 1.09 Impact Factor
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    ABSTRACT: In this paper, entanglement generation by scattering of particles from spin impurities is analyzed. At first, a problem in which an incident particle interacts with an impurity through the Ising and/or Heisenberg interactions is considered. Then, the analysis is extended to investigate the entanglement creation in scattering of particles form two impurities with the same interactions. When the particle is scattered by two impurities, it is shown that a quantum correlation is created between the impurities which is periodic with respect to wavelength of the incident particle. For this case, also it is shown that the Ising interaction is more effective for creating the entanglement between the impurities than the Heisenberg interaction.
    The European Physical Journal D 06/2013; 67(6). · 1.51 Impact Factor
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    ABSTRACT: We investigate the lateral Casimir interaction between two corrugated conductors when they enclose a dielectric slab. The magnitude of the lateral Casimir force can be changed due to the presence of a dielectric slab between them, and it strongly depends on the thickness (d) and dielectric function of the slab and also on the position of the slab with respect to the conductors. In addition, the distance between the conductors (H) and their corrugation wavelengths play important roles in tuning the lateral Casimir interaction. For fixed d and H, quite interestingly, the magnitude of the lateral Casimir force varies when the position of the slab with respect to conductors changes, and it has a maximum when the slab is positioned precisely at the center of the space between the conductors. We find that the interaction decreases when the dielectric constant of the slab increases.
    Physical Review A 08/2012; 86(2). · 3.04 Impact Factor
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    ABSTRACT: Entanglement degradation caused by the Unruh effect is discussed for the tripartite GHZ or W states constructed by modes of a non-interacting quantum field viewed by one inertial observer and two uniformly accelerated observers. For fermionic states, the Unruh effect even for infinite accelerations cannot completely remove the entanglement. However, for the bosonic states, the situation is different and the entanglement vanishes asymptotically. Also, the entanglement is studied for the bipartite subsystems. While for the GHZ states all the bipartite subsystems are identically disentangled, for the W states the bipartite subsystems are somewhat entangled, though, this entanglement can be removed for appropriately accelerated observers. Interestingly, logarithmic negativity as a measure for determining the entanglement of one part of the system relative to the other two parts, is not generally the same for different parts. This means that we encounter tripartite systems where each part is differently entangled to the other two parts. KeywordsUnruh effect–GHZ entanglement–W entanglement–Logarithmic negativity–Bipartite subsystems
    International Journal of Theoretical Physics 01/2012; 51(3):787-804. · 1.09 Impact Factor
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    ABSTRACT: Bipartite entanglement for states of a noninteracting bosonic or fermionic field in the spacetime of a spherically symmetric black hole of Einstein-Gauss-Bonnet gravity is investigated. Although the initial state is chosen to be maximally entangled as the Bell states, the Hawking-Unruh effect causes the state to be mixed and the entanglement degrades, but with different asymptotic behaviors for the fermionic and bosonic fields. The Gauss-Bonnet term with positive α can play an antigravitation role and so this causes a decrease in the Hawking-Unruh effect and consequently reduces the entanglement degradation. On the other hand, the suggested higher dimensions for the spacetime lead to increased entanglement degradation by increasing the dimension. There is a dramatic difference between the behaviors of the entanglement in terms of the radius of the horizon for a five-dimensional black hole and that for higher dimensional black holes. Both bosonic and fermionic fields entanglements are treated beyond the single-mode approximation. Also, the cases where the accelerating observers located at regions near and far from the event horizon of black hole are studied separately.
    Physical review D: Particles and fields 07/2011; 84(2).
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    ABSTRACT: Starting from a Lagrangian, the electromagnetic field in the presence of a nonlinear dielectric medium is quantized using path-integral techniques, and correlation functions of different fields are calculated. The susceptibilities of the nonlinear medium are obtained, and their relations to coupling functions are determined. Finally, the Casimir energy and force in the presence of a nonlinear medium at finite temperature are calculated.
    Physical Review A 03/2011; 50(83):032507. · 3.04 Impact Factor
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    ABSTRACT: Entanglement degradation caused by the Unruh effect is discussed for the tripartite GHZ or W states constructed by modes of a non-interacting quantum field viewed by one inertial observer and two uniformly accelerated observers. For fermionic states, the Unruh effect even for infinite accelerations cannot completely remove the entanglement. However, for the bosonic states, the situation is different and the entanglement vanishes asymptotically. Also, the entanglement is studied for the bipartite subsystems. While for the GHZ states all the bipartite subsystems are identically disentangled, for the W states the bipartite subsystems are somewhat entangled, though, this entanglement can be removed for appropriately accelerated observers. Interestingly, logarithmic negativity as a measure for determining the entanglement of one part of the system relative to the other two parts, is not generally the same for different parts. This means that we encounter tripartite systems where each part is differently entangled to the other two parts.
    03/2011;
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    ABSTRACT: a b s t r a c t By using the path-integral formalism, electromagnetic field in the presence of some linear, isotropic magnetodielectric slabs is quan-tized and related correlation functions are found. In the framework of path-integral techniques, Casimir force between two infinitely large, parallel and ideal conductors, with a different number of magnetodielectric slabs in between, is obtained by calculating the Green's function corresponding to each geometry.
    Annals of Physics 01/2011; · 3.32 Impact Factor
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    F Kheirandish, M Soltani, M Jafari
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    ABSTRACT: Starting from a Lagrangian, an electromagnetic field is quantized in the presence of a medium in thermal equilibrium and also in a medium with time-varying temperature. The vector potential for both equilibrium and nonequilibrium cases is obtained and vacuum fluctuations of the fields are calculated. As an illustrative example, the finite-temperature decay rate and level shift of an atom in a polarizable medium are calculated in this approach.
    Physical Review A 01/2011; 84(84):062120. · 3.04 Impact Factor
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    ABSTRACT: The role of spin-orbit interaction, arises from the Dzyaloshinski-Moriya anisotropic antisymmetric interaction, on the entanglement transfer via an antiferromagnetic XXZ Heisenberg chain is investigated. From symmetrical point of view, the XXZ Hamiltonian with Dzyaloshinski-Moriya interaction can be replaced by a modified XXZ Hamiltonian which is defined by a new exchange coupling constant and rotated Pauli operators. The modified coupling constant and the angle of rotations are depend on the strength of Dzyaloshinski-Moriya interaction. In this paper we study the dynamical behavior of the entanglement propagation through a system which is consist of a pair of maximally entangled spins coupled to one end of the chain. The calculations are performed for the ground state and the thermal state of the chain, separately. In both cases the presence of this anisotropic interaction make our channel more efficient, such that the speed of transmission and the amount of the entanglement are improved as this interaction is switched on. We show that for large values of the strength of this interaction a large family of XXZ chains becomes efficient quantum channels, for whole values of an isotropy parameter in the region $-2 \leq \Delta \leq 2$. Comment: 21 pages, 9 figures
    The European Physical Journal D 10/2010; · 1.51 Impact Factor
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    ABSTRACT: Path-integral formalism is employed to study normal and lateral Casimir interactions in a system composed of a dispersive medium surrounded by two semi-infinite ideal conductors. The dispersive medium is modeled by a continuum of harmonic oscillators, and it is shown that for smooth conductors, the normal force at small distances in the presence of a dispersive medium coincides with the original Casimir force, while at large distances, it tends to the original form with a renormalized coefficient. The correction to the normal force because of the roughness on one of the conductors is calculated. When the inner surfaces of both conductors have roughness, the lateral Casimir interaction occurs because of translational symmetry breaking, which is studied. It is shown that both normal and lateral Casimir forces in the presence of a dispersive medium are weaker in comparison with the original one and are proportional to the roughness amplitude squared. The dependence of the normal and lateral interactions on the memory and strength of the dispersive medium is considered.
    Physical Review A 10/2010; 8250(82):042512. · 3.04 Impact Factor
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    ABSTRACT: We investigate the Casimir effect in the presence of a medium by quantizing the electromagnetic field in the presence of a magnetodielectric medium using the path-integral technique. For a given medium with definite electric and magnetic susceptibilities, explicit expressions for the Casimir force are obtained. The Lifshitz formula is recovered and in the absence of a medium the results tend to the original Casimir force between two conducting parallel plates immersed in the quantum electromagnetic vacuum.
    Physical Review A 05/2010; 8150(84):052110. · 3.04 Impact Factor
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    ABSTRACT: In this paper, by extending the Lagrangian of the Huttner–Barnett model an electromagnetic field in a nonhomogeneous and anisotropic magnetodielectric medium is quantized canonically. In this model, Maxwell equations in the medium are obtained and solved using the Green function technique. The noise operators are found and the results are compared with the phenomenological method.
    Journal of Physics B Atomic and Molecular Physics 01/2009; 42:75504-6.
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    Fardin Kheirandish, Morteza Soltani
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    ABSTRACT: The Huttner-Barnett model is extended to a magnetodielectric medium by adding a matter field to this model. The eigenoperators for the coupled system are calculated and electromagnetic field is written in terms of these operators. The electric and magnetic susceptibilities of the medium are explicitly derived and shown to satisfy the Kramers-Kronig relations. It is shown that the results obtained in this extended model are equivalent to their counterparts obtained in the phenomenological methods.
    Physical Review A 07/2008; · 3.04 Impact Factor
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    Fardin Kheirandish, Morteza Soltani
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    ABSTRACT: It is shown that the minimal coupling method is equivalent to the Huttner-Barnet and phenomenological approaches up to a canonical transformation.
    02/2008;