209 research outputs found
Predicting decoherence in discrete models
The general aim of this paper is to supply a method to decide whether a
discrete system decoheres or not, and under what conditions decoherence occurs,
with no need of appealing to computer simulations to obtain the time evolution
of the reduced state. In particular, a lemma is presented as the core of the
method.Comment: 8 pages, 2 figure
Creation of unstable particles and decoherence in semiclassical cosmology
We consider a simple cosmological model in order to show the importance of
unstable particle creation for the validity of the semiclassical approximation.
Using the mathematical structure of rigged Hilbert spaces we show that particle
creation is the seed of decoherence which enables the quantum to classical
transition.Comment: latex file; 18 pages. Some changes have been added. To appear in Gen.
Rel. and Gra
The arrow of time: from universe time-asymmetry to local irreversible processes
In several previous papers we have argued for a global and non-entropic
approach to the problem of the arrow of time, according to which the ''arrow''
is only a metaphorical way of expressing the geometrical time-asymmetry of the
universe. We have also shown that, under definite conditions, this global
time-asymmetry can be transferred to local contexts as an energy flow that
points to the same temporal direction all over the spacetime. The aim of this
paper is to complete the global and non-entropic program by showing that our
approach is able to account for irreversible local phenomena, which have been
traditionally considered as the physical origin of the arrow of time.Comment: 48 pages, 8 figures, revtex4. Accepted for publication in Foundations
of Physic
Functional Approach to Quantum Decoherence and the Classical Final Limit
For a wide set of quantum systems it is demonstrated that the quantum regime
can be considered as the transient phase while the final classical statistical
regime is a permanent state. A basis where exact matrix decoherence appears for
these final states is found. The relation with the decoherence of histories
formalism is studied. A set of final intrinsically consistent histories is
found.Comment: 20 pages. Phys. Rev A in press 200
Is the decoherence of a system the result of its interaction with the environment?
According to a usual reading, decoherence is a process resulting from the
interaction between a small system and its large environment where information
and energy are dissipated. The particular models treated in the literature on
the subject reinforce this idea since, in general, the behavior of a particle
immersed in a large "bath" composed by many particles is studied. The aim of
this letter is to warn against this usual simplified reading. By means of the
analysis of a well-known model, we will show that decoherence may occur in a
system interacting with an environment consisting of only one particle.Comment: 4 Pages, 5 Figure
Renormalization and Short Distance Singular Structure
The relation between renormalization and short distance singular divergencies in quantum field theory is studied. As a consequence a finite theory is presented. It is shown that these divergencies originate from the multiplication of distributions (and worse-defined mathematical objects). Some of them are eliminated when the multiplication is defined based on dimensional regularization, while others disappear when the states are considered as functionals over the observables space. Nonrenormalizable theories turn to be finite, but anyhow they are endowed with infinite arbitrary constants.Fil: Castagnino, Mario Alberto G. J.. Consejo Nacional de InvestigaciĂłnes CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de AstronomĂa y FĂsica del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de AstronomĂa y FĂsica del Espacio; Argentin
Classical limit of non-integrable systems
Self-induced decoherence formalism and the corresponding classical limit are extended from quantum integrable systems to non-integrable ones.Fil: Castagnino, Mario Alberto G. J.. Consejo Nacional de InvestigaciĂłnes CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de AstronomĂa y FĂsica del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de AstronomĂa y FĂsica del Espacio; Argentin
Decoherence, Correlation, and Unstable Quantum States in Semiclassical Cosmology
It is demonstrated that almost any S-matrix of quantum field theory in curved
spaces posses an infinite set of complex poles (or branch cuts). These poles
can be transformed into complex eigenvalues, the corresponding eigenvectors
being Gamow vectors. All this formalism, which is heuristic in ordinary Hilbert
space, becomes a rigorous one within the framework of a properly chosen rigged
Hilbert space. Then complex eigenvalues produce damping or growing factors. It
is known that the growth of entropy, decoherence, and the appearance of
correlations, occur in the universe evolution, but only under a restricted set
of initial conditions. It is proved that the damping factors allow to enlarge
this set up to almost any initial conditions.Comment: 19 pgs. Latex fil
The non-relativistic limit of (central-extended) Poincare group and some consequences for quantum actualization
The nonrelativistic limit of the centrally extended Poincar\'e group is
considered and their consequences in the modal Hamiltonian interpretation of
quantum mechanics are discussed [ O. Lombardi and M. Castagnino, Stud. Hist.
Philos. Mod. Phys 39, 380 (2008) ; J. Phys, Conf. Ser. 128, 012014 (2008) ].
Through the assumption that in quantum field theory the Casimir operators of
the Poincar\'e group actualize, the nonrelativistic limit of the latter group
yields to the actualization of the Casimir operators of the Galilei group,
which is in agreement with the actualization rule of previous versions of modal
Hamiltonian interpretation [ Ardenghi et al., Found. Phys. (submitted)
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