7,750 research outputs found
Classical Signal Model for Quantum Channels
Recently it was shown that the main distinguishing features of quantum
mechanics (QM) can be reproduced by a model based on classical random fields,
so called prequantum classical statistical field theory (PCSFT). This model
provides a possibility to represent averages of quantum observables, including
correlations of observables on subsystems of a composite system (e.g.,
entangled systems), as averages with respect to fluctuations of classical
(Gaussian) random fields. In this note we consider some consequences of PCSFT
for quantum information theory. They are based on the observation \cite{W} of
two authors of this paper that classical Gaussian channels (important in
classical signal theory) can be represented as quantum channels. Now we show
that quantum channels can be represented as classical linear transformations of
classical Gaussian signa
A study on PDC drill bits quality
The quality of innovating PDC (Polycrystalline Diamond Compact) bits materials needs to be determined with accuracy by measuring cutting efficiency and wear rate, both related to the overall mechanical properties. An original approach is developed to encompass cutting efficiency and wear contribution to the overall sample quality. Therefore, a lathe-type test device was used to abrade specific samples from various manufacturers. Post-experiment analyzes are based on models establishing coupled relationships between cutting and friction stresses related to the drag bits excavation mechanism. These models are implemented in order to evaluate cutting efficiency and to estimate wear of the diamond insert. Phase analysis by XRD and finite element simulations were performed to explain the role of physicochemical parameters on the calculated quality factor values. Four main properties of PDC material were studied to explain quality results obtained in this study: cobalt content in samples that characterizes hardness/fracture toughness compromise, undesired phase as tungsten carbide weakening diamond structure, diamond grains sizes and residual stresses distribution affecting abrasion resistance
Brownian Entanglement
We show that for two classical brownian particles there exists an analog of
continuous-variable quantum entanglement: The common probability distribution
of the two coordinates and the corresponding coarse-grained velocities cannot
be prepared via mixing of any factorized distributions referring to the two
particles in separate. This is possible for particles which interacted in the
past, but do not interact in the present. Three factors are crucial for the
effect: 1) separation of time-scales of coordinate and momentum which motivates
the definition of coarse-grained velocities; 2) the resulting uncertainty
relations between the coordinate of the brownian particle and the change of its
coarse-grained velocity; 3) the fact that the coarse-grained velocity, though
pertaining to a single brownian particle, is defined on a common context of two
particles. The brownian entanglement is a consequence of a coarse-grained
description and disappears for a finer resolution of the brownian motion. We
discuss possibilities of its experimental realizations in examples of
macroscopic brownian motion.Comment: 18 pages, no figure
Derivation of the Planck Spectrum for Relativistic Classical Scalar Radiation from Thermal Equilibrium in an Accelerating Frame
The Planck spectrum of thermal scalar radiation is derived suggestively
within classical physics by the use of an accelerating coordinate frame. The
derivation has an analogue in Boltzmann's derivation of the Maxwell velocity
distribution for thermal particle velocities by considering the thermal
equilibrium of noninteracting particles in a uniform gravitational field. For
the case of radiation, the gravitational field is provided by the acceleration
of a Rindler frame through Minkowski spacetime. Classical zero-point radiation
and relativistic physics enter in an essential way in the derivation which is
based upon the behavior of free radiation fields and the assumption that the
field correlation functions contain but a single correlation time in thermal
equilibrium. The work has connections with the thermal effects of acceleration
found in relativistic quantum field theory.Comment: 23 page
Born's rule from measurements of classical signals by threshold detectors which are properly calibrated
The very old problem of the statistical content of quantum mechanics (QM) is
studied in a novel framework. The Born's rule (one of the basic postulates of
QM) is derived from theory of classical random signals. We present a
measurement scheme which transforms continuous signals into discrete clicks and
reproduces the Born's rule. This is the sheme of threshold type detection.
Calibration of detectors plays a crucial role.Comment: The problem of double clicks is resolved; hence, one can proceed in
purely wave framework, i.e., the wave-partcile duality has been resolved in
favor of the wave picture of prequantum realit
Leiomyosarcoma of the breast in a patient with a 10-year-history of cyclophosphamide exposure: a case report
A 50 year old woman with a 10-year history of systemic lupus erythematosus (SLE) and intermittent low-dose cyclophosphamide therapy developed a palpable mass at the periphery of her left breast. Ultrasound guided core biopsy revealed a spindle cell neoplasm characterized on final pathology as a low grade leiomyosarcoma
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
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Observation of a Charge Density Wave Incommensuration Near the Superconducting Dome in Cu_{x}TiSe_{2}.
X-ray diffraction was employed to study the evolution of the charge density wave (CDW) in Cu_{x}TiSe_{2} as a function of copper intercalation in order to clarify the relationship between the CDW and superconductivity. The results show a CDW incommensuration arising at an intercalation value coincident with the onset of superconductivity at around x=0.055(5). Additionally, it was found that the charge density wave persists to higher intercalant concentrations than previously assumed, demonstrating that the CDW does not terminate inside the superconducting dome. A charge density wave peak was observed in samples up to x=0.091(6), the highest copper concentration examined in this study. The phase diagram established in this work suggests that charge density wave incommensuration may play a role in the formation of the superconducting state
Schroedingers equation with gauge coupling derived from a continuity equation
We consider a statistical ensemble of particles of mass m, which can be
described by a probability density \rho and a probability current \vec{j} of
the form \rho \nabla S/m. The continuity equation for \rho and \vec{j} implies
a first differential equation for the basic variables \rho and S. We further
assume that this system may be described by a linear differential equation for
a complex state variable \chi. Using this assumptions and the simplest possible
Ansatz \chi(\rho,S) Schroedingers equation for a particle of mass m in an
external potential V(q,t) is deduced. All calculations are performed for a
single spatial dimension (variable q) Using a second Ansatz \chi(\rho,S,q,t)
which allows for an explict q,t-dependence of \chi, one obtains a generalized
Schroedinger equation with an unusual external influence described by a
time-dependent Planck constant. All other modifications of Schroeodingers
equation obtained within this Ansatz may be eliminated by means of a gauge
transformation. Thus, this second Ansatz may be considered as a generalized
gauging procedure. Finally, making a third Ansatz, which allows for an
non-unique external q,t-dependence of \chi, one obtains Schroedingers equation
with electromagnetic potentials \vec{A}, \phi in the familiar gauge coupling
form. A possible source of the non-uniqueness is pointed out.Comment: 25 pages, no figure
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