arXiv subjects

J. F. M. Mendes

Publications and source records attributed to J. F. M. Mendes.

5 recordsLinked to original sources

arXiv2003

Digital Spectrometry Signal Treatment Applied to a Fiber Optic Resonant Gyroscope for Rate Measurements

The FORG (Fibre Optic Resonant Gyroscope) opeeration principle uses a recirculating ring resonant cavity to get a rotation-induced Sagnac effect enhancement (cited by Ezekiel and Balsamo). It grants to a FORG a comparable sensitivity in relation an I-FOG (Interferometric Fibre Optic Gyroscope)that has the fiber lenght equal a half of finesse factor times longer. Other advantages is despite of thermal drift because the FORG uses less quantity of fibre than the I-FOG, giving to the first less thermal drift sensitivity than the last. The proposal of this work is to show a applied to a FORG technique that simplifies the signal treatment, employing all digital setup, resulting in a maximally flat scale factor. In this investigation are presented over the simulations results, employing the modified digital FM spectrometry techniques by decimation and interpolation techniques over a ring resonator that pursuit a 10 meters SM-PM lenght fiber coil and 10 centimeters of diameter, with a 1550 nanometers laser source. The advantages of these techniques are to simplify the electronic circuitry, offering an upgrade facility, using only one DSP (Digital Signal Processor), realizing all needed functions. The investigation of this method is based in a optical field switching scheme and digital frequency domain spectrometry.

physics.ins-det↗

arXiv2003

Kappa-deformed quantum field theory and Casimir effect

We consider the quantization of a scalar kappa-deformed field up to the point of obtaining an expression for its vacuum energy. The expression is given by the half sum of the field frequencies, as in the non-deformed case, but with the frequencies obeying the kappa-deformed dispersion relation. We consider a set of kappa-deformed Maxwell equations and show that for the purpose of calculating the Casimir energy the Maxwell field, as in the non-deformed case, behaves as a pair of scalar fields. Those results provide a foundation for computing the Casimir energy starting from the the half sum of field frequencies. A method of calculation starting from this expression is briefly described.

hep-th↗

arXiv2003

The relation between effective action and vacuum energy in a kappa-deformed theory

In a quantum field with spacetime invariance governed by the Poincare algebra the one-loop effective action is equal to the sum of zero modes frequencies, which is the vacuum energy of the field. The first Casimir invariant of the Poincare algebra provides the proper time Hamiltonian in Schwinger's proper time representation of the effective action. We consider here a massive neutral scalar field with spacetime invariance governed by the so called kappa-deformed Poincare algebra. We show here that if in the kappa-deformed theory the first Casimir invariant of the algebra is also used as the proper-time hamiltonian the effective action appears with a real and an imaginary part. The real part is equal to half the sum of kappa-deformed zero mode frequencies, which gives the vacuum energy of the kappa-deformed field. In the limit in which the deformation disappears this real part reduces to half of the sum of zero mode frequencies of the usual scalar field. The imaginary part is proportional to the sum of the squares of the kappa-deformed zero mode frequencies. This part is a creation rate of field excitations in the situations in which it gives rise to a finite physically meaningful quantity. This is the case when the field is submitted to boundary conditions and properly renormalized, as we show in a related paper.

hep-th↗

arXiv2003

The creation of kappa deformed electromagnetic radiation from a sum of zero modes

In a related paper we have obtained that the effective action for a kappa-deformed quantum field theory has a real and an imaginary part. The real part is half the sum of the kappa-deformed zero mode frequencies, while the imaginary part is proportional to the sum of the squares of the zero mode frequencies, being proportional to the inverse of kappa. Here we calculate this imaginary part for the kappa-deformed electromagnetic field confined between two perfectly conducting parallel plates. After renormalization this imaginary part gives a creation rate of kappa-deformed electromagnetic radiation. This creation rate goes to zero at the appropriate limits, namely: when the deformation disappears or at infinite separation of the plates. The result agrees with previously obtained results and shed light on them by exhibiting the creation rate as originated in a sum of zero modes. Let us note that due to the rather complicated kappa-deformed electromagnetic dispersion relation we were led to the theorem of the argument in order to sum the squares of the kappa-deformed frequencies.

hep-th↗

arXiv2001

Vacuum confinement at finite temperature for scalar QED in magnetic field and deformed boundary condition

We investigate the Casimir effect at finite temperature for a charged scalar field in the presence of an external uniform and constant magnetic field, perpendicular to the Casimir plates. We have used a boundary condition characterized by a deformation parameter $θ$; for $θ=0$ we have a periodic condition and for $θ=π$, an antiperiodic one, for intermediate values, we have a deformation. The temperature was introduced using the imaginary time formalism and both the lagrangian and free energy were obtained from Schwinger proper time method for computing the effective action. We also computed the permeability and its asymptotic expressions for low and high temperatures.

hep-th↗