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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; · 2.86 Impact Factor
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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 01/2011; 50(83):032507. · 2.88 Impact Factor
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ABSTRACT: Bipartite entanglement for states of a non-interacting 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 $\alpha$ can play an anti-gravitation role and so this
causes to decrease the Hawking-Unruh effect and consequently reduces the
entanglement degradation. On the other hand, the suggested higher dimensions
for the spacetime, lead to more 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.
10/2010;
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ABSTRACT: In this article we investigate the Casimir effect in the presence of a medium
by quantizing the Electromagnetic (EM) field in the presence of a
magnetodielectric medium by using the path integral formalism. For a given
medium with definite electric and magnetic susceptibilities, explicit
expressions for the Casimir force are obtained which are in agree with the
original Casimir force between two conducting parallel plates immersed in the
quantum electromagnetic vacuum.
09/2010;
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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 01/2010; 8150(84):052110. · 2.88 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 01/2010; 8250(82):042512. · 2.88 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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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;
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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 01/2008; · 2.88 Impact Factor
