595 research outputs found
Lamb Shift for static atoms outside a Schwarzschild black hole
We study, by separately calculating the contributions of vacuum fluctuations
and radiation reaction to the atomic energy level shift, the Lamb shift of a
static two-level atom interacting with real massless scalar fields in the
Boulware, Unruh and Hartle-Hawking vacuums outside a Schwarzschild black hole.
We find that in the Boulware vacuum, the Lamb shift gets a correction arising
as a result of the backscattering of vacuum field modes off the space-time
curvature, which is reminiscent of the correction to the Lamb shift induced by
the presence of cavities. However, when the Unruh and Hartle-Hawking vacua are
concerned, our results show that the Lamb shift behaves as if the atom were
irradiated by a thermal radiation or immersed in a thermal bath at the Hawking
temperature, depending on whether the scalar field is in the Unruh or the
Hartle-Hawking vacuum. Remarkably, the thermal radiation is always
backscattered by the space-time geometry.Comment: 14 pages, no figures, to be published in PR
Resonance interaction energy between two accelerated identical atoms in a coaccelerated frame and the Unruh effect
We investigate the resonance interaction energy between two uniformly
accelerated identical atoms, interacting with the scalar field or the
electromagnetic field in the vacuum state, in the reference frame
coaccelerating with the atoms. We assume that one atom is excited and the other
in the ground state, and that they are prepared in their correlated symmetric
or antisymmetric state. Using perturbation theory, we separate, at the second
order in the atom-field coupling, the contributions of vacuum fluctuations and
radiation reaction field to the energy shift of the interacting system. We show
that only the radiation reaction term contributes to the resonance interaction
between the two atoms, while Unruh thermal fluctuations, related to the vacuum
fluctuations contribution, do not affect the resonance interatomic interaction.
We also show that the resonance interaction between two uniformly accelerated
atoms, recently investigated in the comoving (locally inertial) frame, can be
recovered in the coaccelerated frame, without the additional assumption of the
Fulling-Davies-Unruh temperature for the quantum fields (as necessary for the
Lamb-shift, for example). This indicates, in the case considered, the
equivalence between the coaccelerated frame and the locally inertial frame.Comment: 9 page
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