125 research outputs found
Realization of a twin beam source based on four-wave mixing in Cesium
Four-wave mixing (4WM) is a known source of intense non-classical twin beams.
It can be generated when an intense laser beam (the pump) and a weak laser beam
(the seed) overlap in a medium (here cesium vapor), with
frequencies close to resonance with atomic transitions. The twin beams
generated by 4WM have frequencies naturally close to atomic transitions, and
can be intense (gain ) even in the CW pump regime, which is not the case
for PDC phenomenon in non-linear crystals. So, 4WM is well suited
for atom-light interaction and atom-based quantum protocols. Here we present
the first realization of a source of 4-wave mixing exploiting line of
Cesium atoms.Comment: 10 pages, 10 figure
What's wrong with this rebuttal?
A recent rebuttal to criticism of Bell's analysis is shown to be defective by
fault of failure to consider all hypothetical conditions input into the
derivation of Bell Inequalitites.Comment: 2 page
An analog of Heisenberg uncertainty relation in prequantum classical field theory
Prequantum classical statistical field theory (PCSFT) is a model which
provides a possibility to represent averages of quantum observables, including
correlations of observables on subsystems of a composite system, as averages
with respect to fluctuations of classical random fields. PCSFT is a classical
model of the wave type. For example, "electron" is described by electronic
field. In contrast to QM, this field is a real physical field and not a field
of probabilities. An important point is that the prequantum field of e.g.
electron contains the irreducible contribution of the background field, vacuum
fluctuations. In principle, the traditional QM-formalism can be considered as a
special regularization procedure: subtraction of averages with respect to
vacuum fluctuations. In this paper we derive a classical analog of the
Heisenberg-Robertson inequality for dispersions of functionals of classical
(prequantum) fields. PCSFT Robertson-like inequality provides a restriction on
the product of classical dispersions. However, this restriction is not so rigid
as in QM. The quantum dispersion corresponds to the difference between e.g. the
electron field dispersion and the dispersion of vacuum fluctuations. Classical
Robertson-like inequality contains these differences. Hence, it does not imply
such a rigid estimate from below for dispersions as it was done in QM
Possible Experience: from Boole to Bell
Mainstream interpretations of quantum theory maintain that violations of the
Bell inequalities deny at least either realism or Einstein locality. Here we
investigate the premises of the Bell-type inequalities by returning to earlier
inequalities presented by Boole and the findings of Vorob'ev as related to
these inequalities. These findings together with a space-time generalization of
Boole's elements of logic lead us to a completely transparent Einstein local
counterexample from everyday life that violates certain variations of the Bell
inequalities. We show that the counterexample suggests an interpretation of the
Born rule as a pre-measure of probability that can be transformed into a
Kolmogorov probability measure by certain Einstein local space-time
characterizations of the involved random variables.Comment: Published in: EPL, 87 (2009) 6000
Extended Representations of Observables and States for a Noncontextual Reinterpretation of QM
A crucial and problematical feature of quantum mechanics (QM) is
nonobjectivity of properties. The ESR model restores objectivity reinterpreting
quantum probabilities as conditional on detection and embodying the
mathematical formalism of QM into a broader noncontextual (hence local)
framework. We propose here an improved presentation of the ESR model containing
a more complete mathematical representation of the basic entities of the model.
We also extend the model to mixtures showing that the mathematical
representations of proper mixtures does not coincide with the mathematical
representation of mixtures provided by QM, while the representation of improper
mixtures does. This feature of the ESR model entails that some interpretative
problems raising in QM when dealing with mixtures are avoided. From an
empirical point of view the predictions of the ESR model depend on some
parameters which may be such that they are very close to the predictions of QM
in most cases. But the nonstandard representation of proper mixtures allows us
to propose the scheme of an experiment that could check whether the predictions
of QM or the predictions of the ESR model are correct.Comment: 17 pages, standard latex. Extensively revised versio
Understanding quantization: a hidden variable model
We argue that to solve the foundational problems of quantum theory one has to
first understand what it means to quantize a classical system. We then propose
a quantization method based on replacement of deterministic c-numbers by
stochastically-parameterized c-numbers. Unlike canonical quantization, the
method is free from operator ordering ambiguity and the resulting quantum
system has a straightforward interpretation as statistical modification of
ensemble of classical trajectories. We then develop measurement without wave
function collapse \`a la pilot-wave theory and point out new testable
predictions.Comment: 16 pages, based on a talk given at "Emergent Quantum Mechanics (Heinz
von Foerster Conference 2011)", see http://iopscience.iop.org/1742-6596/361/
A Hilbert Space Representation of Generalized Observables and Measurement Processes in the ESR Model
The extended semantic realism (ESR) model recently worked out by one of the
authors embodies the mathematical formalism of standard (Hilbert space) quantum
mechanics in a noncontextual framework, reinterpreting quantum probabilities as
conditional instead of absolute. We provide here a Hilbert space representation
of the generalized observables introduced by the ESR model that satisfy a
simple physical condition, propose a generalization of the projection
postulate, and suggest a possible mathematical description of the measurement
process in terms of evolution of the compound system made up of the measured
system and the measuring apparatus.Comment: 12 pages, Standard Latex, Minor revision
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