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F. Tamburini

Publications and source records attributed to F. Tamburini.

At least 19 recordsLinked to original sources
arXiv2021

Quantum oscillations in the black hole horizon

By applying Rosen's quantization approach to the historical Oppenheimer and Snyder gravitational collapse and by setting the constraints for the formation of the Schwarzschild black hole (SBH), in a previous paper [1] two of the Authors (CC and FF) found the gravitational potential, the Schrodinger equation, the solution for the energy levels, the area quantum and the quantum representation of the ground state at the Planck scale of the SBH. Such results are consistent with previous ones in the literature. It was also shown that the traditional classical singularity in the core of the SBH is replaced by a quantum oscillator describing a non-singular two-particle system where the two components, named the "nucleus" and the "electron", strongly interact with each other through a quantum gravitational interaction. In agreement with the de Broglie hypothesis, the "electron" is interpreted in terms of the quantum oscillations of the BH horizon. In other words, the SBH should be the gravitational analogous of the hydrogen atom. In this paper, it is shown that these results allow us to compute the SBH entropy as a function of the BH principal quantum number in terms of Bekenstein-Hawking entropy and three sub-leading corrections. In addition, the coefficient of the formula of Bekenstein-Hawking entropy is reduced to a quarter of the traditional value. Then, it is shown that, by performing a correct rescaling of the energy levels, the semi-classical Bohr-like approach to BH quantum physics, previously developed by one of the Authors (CC), is consistent with the obtained results for large values of the BH principal quantum number. After this, Hawking radiation will be analysed by discussing its connection with the BH quantum structure. Finally, it is shown that the time evolution of the above mentioned system solves the BH information paradox.

gr-qc↗
arXiv2020

On the quantization of the extremal Reissner-Nordstrom black hole

Following Rosen's quantization rules, two of the Authors (CC and FF) recently described the Schwarzschild black hole (BH) formed after the gravitational collapse of a pressureless "star of dust" in terms of a "gravitational hydrogen atom". Here we generalize this approach to the gravitational collapse of a charged object, namely, to the geometry of a Reissner-Nordstrom BH (RNBH) and calculate the gravitational potential, the Schrödinger equation and the exact solutions of the energy levels of the gravitational collapse. By using the concept of BH effective state, previously introduced by one of us (CC), we describe the quantum gravitational potential, the mass spectrum and the energy spectrum for the extremal RNBH. The area spectrum derived from the mass spectrum finds agreement with a previous result by Bekenstein. The stability of these solutions, described with the Majorana approach to the Archaic Universe scenario, show the existence of oscillatory regimes or exponential damping for the evolution of a small perturbation from a stable state.

gr-qc↗
arXiv2019

Dark Universe and distribution of Matter as Quantum Imprinting: the Quantum Origin of Universe

In this paper we analyze the Dark Matter problem and the distribution of matter through two different approaches, which are linked by the possibility that the solution of these astronomical puzzles should be sought in the quantum imprinting of the Universe. The first approach is based on a cosmological model formulated and developed in the last ten years by the first and third authors of this paper; the so-called Archaic Universe. The second approach was formulated by Rosen in 1933 by considering the Friedmann-Einstein equations as a simple one-dimensional dynamical system reducing the cosmological equations in terms of a Schroedinger equation. As an example, the quantum memory in cosmological dynamics could explain the apparently periodic structures of the Universe while Archaic Universe shows how the quantum phase concernts not only an ancient era of the Universe, but quantum facets permeating the entire Universe today.

gr-qc↗
arXiv2016

A general theorem on the divergence of vortex beams

The propagation and divergence properties of beams carrying orbital angular momentum (OAM) play a crucial role in many applications. Here we present a general study on the divergence of optical beams with OAM. We show that the mean absolute value of the OAM imposes a lower bound on the value of the beam divergence. We discuss our results for two different definitions of the divergence, the so called rms or encircled-energy. The bound on the rms divergence can be expressed as a generalized uncertainty principle, with applications in long-range communication, microscopy and 2D quantum systems.

quant-ph↗
arXiv2015

The physics of angular momentum radio

Wireless communications, radio astronomy and other radio science applications are predominantly implemented with techniques built on top of the electromagnetic linear momentum (Poynting vector) physical layer. As a supplement and/or alternative to this conventional approach, techniques rooted in the electromagnetic angular momentum physical layer have been advocated, and promising results from proof-of-concept radio communication experiments using angular momentum were recently published. This sparingly exploited physical observable describes the rotational (spinning and orbiting) physical properties of the electromagnetic fields and the rotational dynamics of the pertinent charge and current densities. In order to facilitate the exploitation of angular momentum techniques in real-world implementations, we present a systematic, comprehensive theoretical review of the fundamental physical properties of electromagnetic angular momentum observable. Starting from an overview that puts it into its physical context among the other Poincaré invariants of the electromagnetic field, we describe the multi-mode quantized character and other physical properties that sets electromagnetic angular momentum apart from the electromagnetic linear momentum. These properties allow, among other things, a more flexible and efficient utilization of the radio frequency spectrum. Implementation aspects are discussed and illustrated by examples based on analytic and numerical solutions.

physics.optics↗
arXiv2013

Experimental demonstration of free-space information transfer using phase modulated orbital angular momentum radio

In a series of fundamental proof-of-principle experiments, comprising numerical, controlled laboratory, and real-world experimentation, we have shown that it is possible to use the angular momentum physical layer for radio science and radio communication applications. Here we report a major, decisive step toward the realization of the latter, in the form of the real-world experimental demonstration that a radio beam carrying orbital angular momentum (OAM) can readily be digitally phase shift modulated and that the information thus encoded can be effectively transferred in free space to a remote receiver. The experiment was carried out in an urban setting and showed that the information transfer is robust against ground reflections and interfering radio signals. The importance of our results lies in the fact that digital phase shift keying (PSK) protocols are used in many present-day wireless communication scenarios, allowing new angular momentum radio implementations to use methods and protocols that are backward compatible with existing linear momentum ones.

physics.class-ph↗
arXiv2011

Storming Majorana's Tower with OAM states of light in a plasma

We extend the relationship between mass and spin angular momentum, described by the bosonic spectrum of positive definite mass particles of the Majorana solution to the Dirac equation, to photons that acquire an effective Proca mass through the Anderson-Higgs mechanism when they propagate in a plasma. In an earlier paper we showed that if the plasma is structured, it can impart orbital angular momentum (OAM) to the photons that reduces the total Proca photon mass. Here we show, through a generalisation of Majorana's solution, that photons with OAM in a plasma cannot assume negative squared mass states. This means that there exist interesting analogies with Quantum Gravity or General Relativity models involving a modified action of the Lorentz group.

quant-ph↗
arXiv2011

Tachyonic Majorana neutrinos or neutrino spin-to-orbital angular momentum conversion in OPERA

The new data release of OPERA - CNGS experiment, obtained with a shorter spill of protons, confirms the tachyionic behavior expected from the phenomenological model of a Majorana neutrino with a fictitious imaginary mass term acquired during the propagation in the Earth's crust, recently presented by us. We performed numerical simulations of neutrino event detections to compare the properties of these Majorana tachyons with the new OPERA results, finding a good agreement. The possibility of spin-to orbital angular momentum conversion that is expected to give a negative squared mass in a medium, is also briefly discussed.

hep-ph↗
arXiv2011

Apparent Lorentz violation with superluminal Majorana neutrinos at OPERA?

From the data release of OPERA - CNGS experiment, and publicly announced on 23 September 2011, we cast a phenomenological model based on a Majorana neutrino state carrying a fictitious imaginary mass term, already discussed by Majorana in 1932. This mass term can be induced by the interaction with the matter of the Earth's crust during the 735 Km travel. Within the experimental errors, we prove that the model fits with OPERA, MINOS and supernova SN1987a data. Possible violations to Lorentz invariance due to quantum gravity effects have been considered.

hep-ph↗
arXiv2011

Photon Orbital Angular Momentum and Proca effects in rotating and charged spacetimes

We analyze the effect of Proca mass and orbital angular momentum of photons imposed by a structured plasma in Kerr-Newman and Reissner-Nordstrom-de Sitter spacetimes. The presence of characteristic lengths in a turbulent plasma converts the virtual Proca photon mass on orbital angular momentum, with the result of decreasing the virtual photon mass. The combination of this plasma effect and that of the gravitational field leads to a new astrophysical phenomenon that imprints a specific distribution of orbital angular momentum into different frequencies of the light emitted from the neighborhood of such a black hole. The determination of the orbital angular momentum spectrum of the radiation in different frequency bands leads to a complete characterization of the electrostatic and gravitational field of the black hole and of the plasma turbulence, with fundamental astrophysical and cosmological implications.

gr-qc↗
arXiv2010

Wavelet and R/S analysis of the X-ray flickering of cataclysmic variables

Recently, wavelets and R/S analysis have been used as statistical tools to characterize the optical flickering of cataclysmic variables. Here we present the first comprehensive study of the statistical properties of X-ray flickering of cataclysmic variables in order to link them with physical parameters. We analyzed a sample of 97 X-ray light curves of 75 objects of all classes observed with the XMM-Newton space telescope. By using the wavelets analysis, each light curve has been characterized by two parameters, alpha and Sigma, that describe the energy distribution of flickering on different timescales and the strength at a given timescale, respectively. We also used the R/S analysis to determine the Hurst exponent of each light curve and define their degree of stochastic memory in time. The X-ray flickering is typically composed of long time scale events (1.5 < alpha < 3), with very similar strengths in all the subtypes of cataclysmic variables (-3 < Sigma < -1.5). The X-ray data are distributed in a much smaller area of the alpha-Sigma parameter space with respect to those obtained with optical light curves. The tendency of the optical flickering in magnetic systems to show higher Sigma values than the non-magnetic systems is not encountered in the X-rays. The Hurst exponents estimated for all light curves of the sample are larger than those found in the visible, with a peak at 0.82. In particular, we do not obtain values lower than 0.5. The X-ray flickering presents a persistent memory in time, which seems to be stronger in objects containing magnetic white dwarf primaries. The similarity of the X-ray flickering in objects of different classes together with the predominance of a persistent stochastic behavior can be explained it terms of magnetically-driven accretion processes acting in a considerable fraction of the analyzed objects.

astro-ph.SR↗
arXiv2010

Photon Orbital Angular Momentum and Mass in a Plasma Vortex

We analyse the Anderson-Higgs mechanism of photon mass acquisition in a plasma and study the contribution to the mass from the orbital angular momentum acquired by a beam of photons when it crosses a spatially structured charge distribution. To this end we apply Proca-Maxwell equations in a static plasma with a particular spatial distribution of free charges, notably a plasma vortex, that is able to impose orbital angular momentum (OAM) onto light. In addition to the mass acquisition of the conventional Anderson-Higgs mechanism, we find that the photon acquires an additional mass from the OAM and that this mass reduces the Proca photon mass.

physics.plasm-ph↗
arXiv2010

Linear and angular momentum of electromagnetic fields generated by an arbitrary distribution of charge and current densities at rest

Starting from Stratton-Panofsky-Phillips-Jefimenko equations for the electric and magnetic fields generated by completely arbitrary charge and current density distributions at rest, we derive far-zone approximations for the fields, containing all components, dominant as well as sub-dominant. Using these approximate formulas, we derive general formulas for the total electromagnetic linear momentum and angular momentum, valid at large distances from arbitrary, non-moving charge and current sources.

physics.class-ph↗
arXiv2009

Method to measure off-axis displacements based on the analysis of the intensity distribution of a vortex beam

We study the properties of the Fraunhofer diffraction patterns produced by Gaussian beams crossing spiral phase plates. We show, both analytically and numerically, that off-axis displacements of the input beam produce asymmetric diffraction patterns. The intensity profile along the direction of maximum asymmetry shows two different peaks. We find that the intensity ratio between these two peaks decreases exponentially with the off-axis displacement of the incident beam, the decay being steeper for higher strengths of the optical singularity of the spiral phase plate. We analyze how this intensity ratio can be used to measure small misalignments of the input beam with a very high precision.

physics.optics↗
arXiv2009

Analysis of the white--light flickering of the Intermediate Polar V709 Cas with wavelets and Hurst analysis

We characterize the flickering observed in the optical lightcurve of the Intermediate Polar system V709 Cas by determining its position in the alpha-Sigma as in the Fritz and Bruch (1998) classification scheme. Sigma represents the strength of flickering at a given timescale, while alpha describes the energy distribution of the flickering at different time scales. Here alpha is independently obtained with both the wavelets and the Hurst R/S analysis. The flickering shows self-similarity in the time scale ranging from tens of minutes down to 10 seconds with stochastic persistent memory in time. alpha and Sigma appear anticorrelated. In the alpha-Sigma diagram V709 Cas falls in the region of magnetic systems. Since V709 Cas shows the spin period of the magnetic WD only in the X-ray but not in the optical, we conclude that this method can be used to characterize CV subtypes especially when their classification is uncertain.

astro-ph.SR↗
arXiv2008

Diversity among other worlds: characterization of exoplanets by direct detection

The physical characterization of exoplanets will require to take spectra at several orbital positions. For that purpose, a direct imaging capability is necessary. Direct imaging requires an efficient stellar suppression mechanism, associated with an ultrasmooth telescope. We show that before future large space missions (interferometer, 4-8 m class coronograph, external occulter or Fresnel imager), direct imaging of giant planets and close-by super-Earth are at the cross-road of a high scientific interest and a reasonable feasibility. The scientific interest lies in the fact that super-Earths share common geophysical attributes with Earths. They already begin to be detected by radial velocity (RV) and, together with giant planets, they have a larger area than Earths, making them detectable with a 1.5-2 m class telescope in reflected light. We propose such a (space) telescope be a first step before large direct imaging missions.

astro-ph↗