2,755 research outputs found
Magnon-Phonon Quantum Correlation Thermometry
A large fraction of quantum science and technology requires low-temperature environments such as those afforded by dilution refrigerators. In these cryogenic environments, accurate thermometry can be difficult to implement, expensive, and often requires calibration to an external reference. Here, we theoretically propose a primary thermometer based on measurement of a hybrid system consisting of phonons coupled via a magnetostrictive interaction to magnons. Thermometry is based on a cross-correlation measurement in which the spectrum of back-action driven motion is used to scale the thermomechanical motion, providing a direct measurement of the phonon temperature independent of experimental parameters. Combined with a simple low-temperature compatible microwave cavity readout, this primary thermometer is expected to become a promising alternative for thermometry below 1 K
Cosmology in GSG
We describe what cosmology looks like in the context of the geometric theory
of gravity (GSG) based on a single scalar field. There are two distinct classes
of cosmological solutions. An interesting feature is the possibility of having
a bounce without invoking exotic equations of state for the cosmic fluid. We
also discuss cosmological perturbation and present the basis of structure
formation by gravitational instability in the framework of the geometric scalar
gravity.Comment: 12 pages, 5 figures, accepted for publication in Phys. Rev.
More about scalar gravity
We discuss a class of models for gravity based on a scalar field. The models
include and generalize the old approach by Nordstr\"om which predated and in
some way inspired General Relativity. The class include also a model that we
have recently introduced and discussed in its cosmological aspects (GSG). We
present here a complete characterisation of the Schwarschild geometry as a
vacuum solution of GSG and sketch a discussion of the first Post-Newtonian
approximation.Comment: 11 pages, 1 figure, accepted for publication in PR
Geometric scalar theory of gravity
We present a geometric scalar theory of gravity. Our proposal will be
described using the "background field method" introduced by Gupta, Feynman and
others as a field theory formulation of general relativity. We analyze previous
criticisms against scalar gravity and show how the present proposal avoids
these difficulties. This concerns not only the theoretical complaints but also
those related to observations. In particular, we show that the widespread
belief of the conjecture that the source of scalar gravity must be the trace of
the energy-momentum tensor - which is one of the main difficulties to couple
gravity with electromagnetic phenomenon in previous models - does not apply to
our geometric scalar theory. Some consequences of the new scalar theory are
explored.Comment: We did some modifications which do not change the content of the tex
Maximal correlation between flavor entanglement and oscillation damping due to localization effects
Localization effects and quantum decoherence driven by the mass-eigenstate
wave packet propagation are shown to support a statistical correlation between
quantum entanglement and damped oscillations in the scenario of three-flavor
quantum mixing for neutrinos. Once the mass-eigenstates that support flavor
oscillations are identified as three-{\em qubit} modes, a decoherence scale can
be extracted from correlation quantifiers, namely the entanglement of formation
and the logarithmic negativity. Such a decoherence scale is compared with the
coherence length of damped oscillations. Damping signatures exhibited by flavor
transition probabilities as an effective averaging of the oscillating terms are
then explained as owing to loss of entanglement between mass modes involved in
the relativistic propagation.Comment: 13 pages, 03 figure
Tratamento do problema de contato-impacto entre corpos flexĂveis em grandes deformações pelo mĂ©todo dos elementos finitos
O tratamento do problema de contato entre corpos flexĂveis foi implementado no mĂłdulo
METAFOR4, que permite o tratamento de problemas de conformacáo mecanica. O presente
algoritmo emprega o método da penalidade para o cálculo de forcas de contato. Os elementos de contato sáo percorridos duas vezes em cada passo de tempo para que seja assegurada a deteccáo de todas as formas de interpenetracao. O algoritmo apresentou-se extremamente robusto. Um exemplo de impacto entre um tubo e uma placa é mostrado.The treatment of the contact problem between flexible bodies has been implemented in the
METAFOR modulus4, which allows the treatment of metal forming problems. The described
algorithm uses the penalty method for the calculation of the contact forces. The contact elements are checked twice at each time step to assure the detection of al1 forms of penetration. The algorithm demonstrated to be extremely robust. An example of impact between a tube and a plate is given.Peer Reviewe
Tratamento do problema de contato-impacto entre corpos flexĂveis em grandes deformações pelo mĂ©todo dos elementos finitos
O tratamento do problema de contato entre corpos flexĂveis foi implementado no mĂłdulo
METAFOR4, que permite o tratamento de problemas de conformacáo mecanica. O presente
algoritmo emprega o método da penalidade para o cálculo de forcas de contato. Os elementos de contato sáo percorridos duas vezes em cada passo de tempo para que seja assegurada a deteccáo de todas as formas de interpenetracao. O algoritmo apresentou-se extremamente robusto. Um exemplo de impacto entre um tubo e uma placa é mostrado.The treatment of the contact problem between flexible bodies has been implemented in the
METAFOR modulus4, which allows the treatment of metal forming problems. The described
algorithm uses the penalty method for the calculation of the contact forces. The contact elements are checked twice at each time step to assure the detection of al1 forms of penetration. The algorithm demonstrated to be extremely robust. An example of impact between a tube and a plate is given.Peer Reviewe
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