Thermal effects on the stability of excited atoms in cavities

Khanna, F. C.; Malbouisson, A. P. C.; Malbouisson, J. M. C.; Santana, A. E.

doi:10.1103/physreva.81.032119

Cited by 8 publications

(21 citation statements)

References 36 publications

(64 reference statements)

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“…Under these assumptions, it results that the reduced density matrix does not depend on temperature. In contrast, employing methods and relying on results obtained in [2] and [3], one finds that the individual dressed atoms in the bipartite system are very little affected by heating for temperatures of about 300 K. The overall conclusion is that the methods and results from [1] are valid if we consider the system at room temperatures. * adolfo@cbpf.br Our bipartite system is composed of two subsystems, A and B; the subsystems consist of dressed atoms A and B, respectively, and the whole system is contained in a perfectly reflecting sphere of radius R in thermal equilibrium with an environment (field) at a temperature β −1 .…”

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confidence: 94%

“…(9) for the time evolution of the first-level excited atomic states. The choice of the Bose-Einstein distribution to the field modes can be justified: in the case of an arbitrarily large cavity, the dressed field modes coincide with the bare ones [2], and in the limit of vanishing coupling with the atom, these modes follow the Bose-Einstein distribution exactly. Strictly speaking, this is not the case for the coupled atom-field system in a finite cavity.…”

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confidence: 99%

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Addendum to “Behavior of a bipartite system in a cavity”

Linhares

Malbouisson

2010

Phys. Rev. A

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This note is an Addendum to our previous article [Phys. Rev. A 81, 053820 (2010)]. We show that under the assumption of a Bose-Einstein distribution for the thermal reservoir, zero-temperature properties of the entangled states considered there are not changed by heating, for temperatures up to the order of room temperatures. In this case, the system is dissipative in free space and presents stability for a small cavity, both for T = 0 and for finite temperature.In this note we consider how heating could affect the properties of the bipartite system studied in [1]. This bipartite system consists of two dressed atoms inside a reflecting cavity that do not interact with each other, only with an environmental field. Our approach to this problem makes use of the notion of dressed thermal states [2], in the context of a model already employed in the literature, of atoms-or, more generally, material particles-in the harmonic approximation, coupled to an environment modeled by an infinite set of pointlike harmonic oscillators (the field modes). The dressed thermal state approach is an extension of the dressed (zerotemperature) formalism that was introduced earlier. The reader is referred to [1] and [2] for details of our formalism.Here we consider entanglement as a pure quantum effect, a characteristic of quantum mechanics, which is also nonlocal, in the sense that distant and noninteracting systems may be entangled. This is due to the physical meaning attributed to superposed states, a concept with no correspondence in classical physics, and not to the interaction between the (in our case, dressed) atoms. Indeed, such properties of entanglement of noninteracting systems have been used in the realm of teleportation and quantum information theory and to conceive quantum communication devices. We think that investigation the measure to which the properties of such systems are affected by heating is important, particularly in the case of room temperatures. The possibility of constructing such devices at temperatures of everyday life would be an interesting matter.In this note we remain on theoretical grounds and perform a study of thermal effects on our bipartite system, assuming that the dressing fields of the atoms obey a Bose-Einstein distribution and that the first-level excited dressed atomic states evolve in the same way as in [1]. Under these assumptions, it results that the reduced density matrix does not depend on temperature. In contrast, employing methods and relying on results obtained in [2] and [3], one finds that the individual dressed atoms in the bipartite system are very little affected by heating for temperatures of about 300 K. The overall conclusion is that the methods and results from [1] are valid if we consider the system at room temperatures. * adolfo@cbpf.br Our bipartite system is composed of two subsystems, A and B; the subsystems consist of dressed atoms A and B, respectively, and the whole system is contained in a perfectly reflecting sphere of radius R in thermal equilibrium with an environme...

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confidence: 94%

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confidence: 99%

Addendum to “Behavior of a bipartite system in a cavity”

Linhares

Malbouisson

2010

Phys. Rev. A

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“…11,12 In this case, perturbative renormalizability is not an absolute criterion for the existence of the model. [50][51][52] We point out that for D = 1 + 2, although not perturbatively renormalizable the model has been shown to exist and was constructed.…”

Section: The Bosonized Gross-neveu Modelmentioning

confidence: 99%

“…In previous works, [1][2][3][4][5][6][7][8][9][10][11][12][13][14] when investigating phase transitions in films, periodic or antiperiodic boundary conditions for spatial coordinates have been used in analogy with the imposed condition on the imaginary-time variable. According to the KMS condition, 15 the boundary conditions on imaginary time are restricted to be periodic for bosons and antiperiodic for fermions.…”

Section: Introductionmentioning

confidence: 99%

Properties of size-dependent models having quasiperiodic boundary conditions

Cavalcanti

Linhares

Malbouisson

2018

Int. J. Mod. Phys. A

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Boundary conditions effects are explored for size-dependent models in thermal equilibrium. Scalar and fermionic models are used for D = 1 + 3 (films), D = 1 + 2 (hollow cylinder) and D = 1 + 1 (ring). For all models a minimal length is found, below which no thermally-induced phase transition occurs. Using quasiperiodic boundary condition controlled by a contour parameter θ (θ = 0 is a periodic boundary condition and θ = 1 is an antiperiodic condition) it results that the minimal length depends directly on the value of θ. It is also argued that this parameter can be associated to an Aharonov-Bohm phase.

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“…[19] as a method to account, in a nonperturbative way, for the oscillator radiation process in free space. In subsequent works, the concept was used to study the spontaneous emission of atoms inside small cavities [20], the quantum Brownian motion [21,22], the thermalization process [23][24][25], the time evolution of bipartite systems [26][27][28], the entanglement of biatomic systems [29][30][31], and other related issues [32][33][34][35][36]. For a clear explanation, see reference [33].…”

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Spontaneous Decay of a Dressed Harmonic Oscillator Inside a Spherical Cavity

2020

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We consider a complete study of the influence of the cavity size on the spontaneous decay of an atom excited state, roughly approximated by a harmonic oscillator. We confine the oscillator-field system in a spherical cavity of finite radius, perfectly reflective, and work in the formalism of dressed coordinates and states, which allows performing nonperturbative calculations for the probability of the oscillator to decay spontaneously from the first excited state to the ground state. In free space, we obtain known exact results and, for sufficiently small radii, we have developed a power expansion calculation on this parameter. Furthermore, for cavities of arbitrary size radius, we developed numerical computations and showed a complete agreement of this method with the exact one for free space and the power expansion results for small cavities, in this way showing the robustness of our numerical computations. We have found that, in general, the spontaneous decay of an excited state of the oscillator increases with the cavity size radius and vice versa. For sufficiently small cavities, the oscillator practically does not suffers spontaneous decay, whereas for large cavities, the spontaneous decay approaches the free-space value. On the other hand, for some particular values of the cavity radius, in which the cavity is in resonance with the natural frequency of the atom, the spontaneous decay transition probability is increased compared to the free-space case. Also, we showed how the probability of spontaneous decay goes from an oscillatory time behavior, for finite cavity radius, to almost exponential decay, for free space.

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Thermal effects on the stability of excited atoms in cavities

Cited by 8 publications

References 36 publications

Addendum to “Behavior of a bipartite system in a cavity”

Addendum to “Behavior of a bipartite system in a cavity”

Properties of size-dependent models having quasiperiodic boundary conditions

Spontaneous Decay of a Dressed Harmonic Oscillator Inside a Spherical Cavity

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