12,164 research outputs found
Thermal and non-thermal signatures of the Unruh effect in Casimir-Polder forces
We show that Casimir-Polder forces between two relativistic uniformly
accelerated atoms exhibit a transition from the short distance thermal-like
behavior predicted by the Unruh effect, to a long distance non-thermal
behavior, associated with the breakdown of a local inertial description of the
system. This phenomenology extends the Unruh thermal response detected by a
single accelerated observer to an accelerated spatially extended system of two
particles, and we identify the characteristic length scale for this crossover
with the inverse of the proper acceleration of the two atoms. Our results are
derived separating at fourth order in perturbation theory the contributions of
vacuum fluctuations and radiation reaction field to the Casimir-Polder
interaction between two atoms moving in two generic stationary trajectories
separated by a constant distance, and linearly coupled to a scalar field. The
field can be assumed in its vacuum state or at finite temperature, resulting in
a general method for the computation of Casimir-Polder forces in stationary
regimes.Comment: 6 pages, 1 figure. Revised versio
Statistical transmutation of quantum bosonic strings coupled to general four-dimensional Chern-Simons theory
A bosonic string coupled to the generalized Chern-Simons theory in 3+1D
acquires a magnetic field along itself, when it is closed, and a topological
charge at its extremity, when it is open. We construct the creation operators
for the full quantum field states associated to these strings and determine the
dual algebra satisfied by them. We show that the creation operator fo the
composite state of a quantum closed bosonic string, bearing a magnetic flux,
and a topologically charged open bosonic string, possesses generalized
statistics. The relation of our results with previous approaches to the problem
is also established.Comment: 4 pages, Revtex
Homogeneity of pristine and bromine intercalated graphite fibers
Wide variations in the resistivity of intercalated graphite fibers and to use these materials for electrical applications, their bulk properties must be established. The homogeneity of the diameter, the resistivity, and the mass density of 50 graphite fibers, before and after bromine intercalation was measured. Upon intercalation the diameter was found to expand by about 5%, the resistivity to decrease by a factor of five, and the density to increase by about 6%. Each individual fiber was found to have uniform diameter and resistivity over macroscopic regions for lengths as long as 7 cm. The ratio of pristine to intercalated resistivity increases as the pristine fiber diameter increases at a rate of 0.16 micron, but decreases with the increasing ratio of intercalated diameter to pristine diameter at a rate of 0.08
Explicit Bosonization of the Massive Thirring Model in 3+1 Dimensions
We bosonize the Massive Thirring Model in 3+1D for small coupling constant
and arbitrary mass. The bosonized action is explicitly obtained both in terms
of a Kalb-Ramond tensor field as well as in terms of a dual vector field. An
exact bosonization formula for the current is derived. The small and large mass
limits of the bosonized theory are examined in both the direct and dual forms.
We finally obtain the exact bosonization of the free fermion with an arbitrary
mass.Comment: Latex, 7 page
Charge and Magnetic Flux Correlations in Chern-Simons Theory with Fermions
Charge and magnetic flux bearing operators are introduced in Chern-Simons
theory both in its pure form and when it is coupled to fermions. The magnetic
flux creation operator turns out to be the Wilson line. The euclidean
correlation functions of these operators are shown to be local and are
evaluated exactly in the pure case and through an expansion in the inverse
fermion mass whenever these are present. Physical states only occur in the
presence of fermions and consist of composite charge-magnetic flux carrying
states which are in general anyonic. The large distance behavior of the
correlation functions indicates the condensation of charge and magnetic flux.Comment: Latex, 17 page
Supersymmetric free-damped oscillators: Adaptive observer estimation of the Riccati parameter
A supersymmetric class of free damped oscillators with three parameters has
been obtained in 1998 by Rosu and Reyes through the factorization of the Newton
equation. The supplementary parameter is the integration constant of the
general Riccati solution. The estimation of the latter parameter is performed
here by employing the recent adaptive observer scheme of Besancon et al., but
applied in a nonstandard form in which a time-varying quantity containing the
unknown Riccati parameter is estimated first. Results of computer simulations
are presented to illustrate the good feasibility of this approach for a case in
which the estimation is not easily accomplished by other meansComment: 8 pages, 6 figure
Van der Waals and resonance interactions between accelerated atoms in vacuum and the Unruh effect
We discuss different physical effects related to the uniform acceleration of
atoms in vacuum, in the framework of quantum electrodynamics. We first
investigate the van der Waals/Casimir-Polder dispersion and resonance
interactions between two uniformly accelerated atoms in vacuum. We show that
the atomic acceleration significantly affects the van der Waals force, yielding
a different scaling of the interaction with the interatomic distance and an
explicit time dependence of the interaction energy. We argue how these results
could allow for an indirect detection of the Unruh effect through dispersion
interactions between atoms. We then consider the resonance interaction between
two accelerated atoms, prepared in a correlated Bell-type state, and
interacting with the electromagnetic field in the vacuum state, separating
vacuum fluctuations and radiation reaction contributions, both in the
free-space and in the presence of a perfectly reflecting plate. We show that
nonthermal effects of acceleration manifest in the resonance interaction,
yielding a change of the distance dependence of the resonance interaction
energy. This suggests that the equivalence between temperature and acceleration
does not apply to all radiative properties of accelerated atoms. To further
explore this aspect, we evaluate the resonance interaction between two atoms in
non inertial motion in the coaccelerated (Rindler) frame and show that in this
case the assumption of an Unruh temperature for the field is not required for a
complete equivalence of locally inertial and coaccelerated points of views.Comment: 8 pages, Proceedings of the Eighth International Workshop DICE 2016
Spacetime - Matter - Quantum Mechanic
Quantum global vortex strings in a background field
We consider quantum global vortex string correlation functions, within the
Kalb-Ramond framework, in the presence of a background field-strength tensor
and investigate the conditions under which this yields a nontrivial
contribution to those correlation functions. We show that a background field
must be supplemented to the Kalb-Ramond theory, in order to correctly describe
the quantum properties of the vortex strings. The explicit form of this
background field and the associated quantum vortex string correlation function
are derived. The complete expression for the quantum vortex creation operator
is explicitly obtained. We discuss the potential applicability of our results
in the physics of superfluids and rotating Bose-Einstein condensates.Comment: To appear in Journal of Physics A: Mathematical and Genera
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