414 research outputs found
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)
Explaining the unobserved: why quantum mechanics is not only about information
A remarkable theorem by Clifton, Bub and Halvorson (2003)(CBH) characterizes
quantum theory in terms of information--theoretic principles. According to Bub
(2004, 2005) the philosophical significance of the theorem is that quantum
theory should be regarded as a ``principle'' theory about (quantum) information
rather than a ``constructive'' theory about the dynamics of quantum systems.
Here we criticize Bub's principle approach arguing that if the mathematical
formalism of quantum mechanics remains intact then there is no escape route
from solving the measurement problem by constructive theories. We further
propose a (Wigner--type) thought experiment that we argue demonstrates that
quantum mechanics on the information--theoretic approach is incomplete.Comment: 34 Page
Effects and Propositions
The quantum logical and quantum information-theoretic traditions have exerted
an especially powerful influence on Bub's thinking about the conceptual
foundations of quantum mechanics. This paper discusses both the quantum logical
and information-theoretic traditions from the point of view of their
representational frameworks. I argue that it is at this level, at the level of
its framework, that the quantum logical tradition has retained its centrality
to Bub's thought. It is further argued that there is implicit in the quantum
information-theoretic tradition a set of ideas that mark a genuinely new
alternative to the framework of quantum logic. These ideas are of considerable
interest for the philosophy of quantum mechanics, a claim which I defend with
an extended discussion of their application to our understanding of the
philosophical significance of the no hidden variable theorem of Kochen and
Specker.Comment: Presented to the 2007 conference, New Directions in the Foundations
of Physic
Quantum mechanics is about quantum information
I argue that quantum mechanics is fundamentally a theory about the
representation and manipulation of information, not a theory about the
mechanics of nonclassical waves or particles. The notion of quantum information
is to be understood as a new physical primitive -- just as, following
Einstein's special theory of relativity, a field is no longer regarded as the
physical manifestation of vibrations in a mechanical medium, but recognized as
a new physical primitive in its own right.Comment: 17 pages, forthcoming in Foundations of Physics Festschrift issue for
James Cushing. Revised version: some paragraphs have been added to the final
section clarifying the argument, and various minor clarifying remarks have
been added throughout the tex
A model balancing cooperation and competition explains our right-handed world and the dominance of left-handed athletes
An overwhelming majority of humans are right-handed. Numerous explanations
for individual handedness have been proposed, but this population-level
handedness remains puzzling. Here we use a minimal mathematical model to
explain this population-level hand preference as an evolved balance between
cooperative and competitive pressures in human evolutionary history. We use
selection of elite athletes as a test-bed for our evolutionary model and
account for the surprising distribution of handedness in many professional
sports. Our model predicts strong lateralization in social species with limited
combative interaction, and elucidates the rarity of compelling evidence for
"pawedness" in the animal world.Comment: 5 pages of text and 3 figures in manuscript, 8 pages of text and two
figures in supplementary materia
This elusive objective existence
Zurek's existential interpretation of quantum mechanics suffers from three
classical prejudices, including the belief that space and time are
intrinsically and infinitely differentiated. They compel him to relativize the
concept of objective existence in two ways. The elimination of these prejudices
makes it possible to recognize the quantum formalism's ontological implications
- the relative and contingent reality of spatiotemporal distinctions and the
extrinsic and finite spatiotemporal differentiation of the physical world -
which in turn makes it possible to arrive at an unqualified objective
existence. Contrary to a widespread misconception, viewing the quantum
formalism as being fundamentally a probability algorithm does not imply that
quantum mechanics is concerned with states of knowledge rather than states of
Nature. On the contrary, it makes possible a complete and strongly objective
description of the physical world that requires no reference to observers. What
objectively exists, in a sense that requires no qualification, is the
trajectories of macroscopic objects, whose fuzziness is empirically irrelevant,
the properties and values of whose possession these trajectories provide
indelible records, and the fuzzy and temporally undifferentiated states of
affairs that obtain between measurements and are described by counterfactual
probability assignments.Comment: To appear in IJQI; 21 pages, LaTe
Reconstructing Bohr's Reply to EPR in Algebraic Quantum Theory
Halvorson and Clifton have given a mathematical reconstruction of Bohr's
reply to Einstein, Podolsky and Rosen (EPR), and argued that this reply is
dictated by the two requirements of classicality and objectivity for the
description of experimental data, by proving consistency between their
objectivity requirement and a contextualized version of the EPR reality
criterion which had been introduced by Howard in his earlier analysis of Bohr's
reply. In the present paper, we generalize the above consistency theorem, with
a rather elementary proof, to a general formulation of EPR states applicable to
both non-relativistic quantum mechanics and algebraic quantum field theory; and
we clarify the elements of reality in EPR states in terms of Bohr's
requirements of classicality and objectivity, in a general formulation of
algebraic quantum theory.Comment: 13 pages, Late
Quantum Mechanics as a Framework for Dealing with Uncertainty
Quantum uncertainty is described here in two guises: indeterminacy with its
concomitant indeterminism of measurement outcomes, and fuzziness, or
unsharpness. Both features were long seen as obstructions of experimental
possibilities that were available in the realm of classical physics. The birth
of quantum information science was due to the realization that such
obstructions can be turned into powerful resources. Here we review how the
utilization of quantum fuzziness makes room for a notion of approximate joint
measurement of noncommuting observables. We also show how from a classical
perspective quantum uncertainty is due to a limitation of measurability
reflected in a fuzzy event structure -- all quantum events are fundamentally
unsharp.Comment: Plenary Lecture, Central European Workshop on Quantum Optics, Turku
2009
Jump-like unravelings for non-Markovian open quantum systems
Non-Markovian evolution of an open quantum system can be `unraveled' into
pure state trajectories generated by a non-Markovian stochastic (diffusive)
Schr\"odinger equation, as introduced by Di\'osi, Gisin, and Strunz. Recently
we have shown that such equations can be derived using the modal (hidden
variable) interpretation of quantum mechanics. In this paper we generalize this
theory to treat jump-like unravelings. To illustrate the jump-like behavior we
consider a simple system: A classically driven (at Rabi frequency )
two-level atom coupled linearly to a three mode optical bath, with a central
frequency equal to the frequency of the atom, , and the two side
bands have frequencies . In the large limit we
observed that the jump-like behavior is similar to that observed in this system
with a Markovian (broad band) bath. This is expected as in the Markovian limit
the fluorescence spectrum for a strongly driven two level atom takes the form
of a Mollow triplet. However the length of time for which the Markovian-like
behaviour persists depends upon {\em which} jump-like unraveling is used.Comment: 11 pages, 5 figure
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