1,347 research outputs found
Addendum: Behavior of a bipartite system in a cavity
This note is an Addendum to our previous article [Phys. Rev. A \textbf{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.Comment: Revtex, 04 pages no figures, Version as accepted for publication in
Phys. Rev.
A note on the infrared behavior of the compactified Ginzburg--Landau model in a magnetic field
We consider the Euclidean large- Ginzburg--Landau model in dimensions,
() of them being compactified. For D=3, the system can be supposed
to describe, in the cases of d=1, d=2, and d=3, respectively, a superconducting
material in the form of a film, of an infinitely long wire having a rectangular
cross-section and of a brick-shaped grain. We investigate the fixed-point
structure of the model, in the presence of an external magnetic field. An
infrared-stable fixed points is found, which is independent of the number of
compactified dimensions. This generalizes previous work for type-II
superconducting filmsComment: LATEX, 6 pages no figures. arXiv admin note: 80% of text overlaps
with arXiv:1102.139
Finite-size, magnetic and chemical-potential effects on first-order phase transitions
We perform a study about effects of an applied magnetic field and a finite
chemical potential on the size-dependent phase structure of a first-order
transition. These effects are introduced by using methods of quantum fields
defined on toroidal spaces, and we study in particular the case of two
compactified dimensions, imaginary time and a spatial one (a heated film). It
is found that for any value of the applied field, there is a minimal size of
the system, independent of the chemical potential, below which the transition
disappears.Comment: 19 pages, 3 figures, version accepted for publication in Phys. Lett.
Behavior of a bipartite system in a cavity
We study the time evolution of a superposition of product states of two
dressed atoms in a spherical cavity in the situations of an arbitrarily large
cavity (free space) and of a small one. In the large-cavity case, the system
dissipates, whereas, for the small cavity, the system evolves in an oscillating
way and never completely decays. We verify that the von Neumann entropy for
such a system does not depend on time, nor on the size of the cavityComment: 9 pages 2 figures, Revtex, Version accepted to be published in
Physical Review
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