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Severini, S.
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Severini, S.
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- PublicationOpen AccessSOLENOIDALITÀ DEL CAMPO DI INDUZIONE MAGNETICA E CONSERVAZIONE DELLA QUANTITÀ DI MOTO TOTALE(UNIPRESS Casa Editrice e libreria Online Padova, 2012-05-30)
; ; ;Severini, S.; C.I.S.A.M. – R.T.O. /Divisione E.M.C. Via Bigattiera Lato Monte 10 56122 S.Piero a Grado (PI), ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; ; ; ;Monorchio, A.; Dipartimento di Ingegneria dell'Informazione Universita` di Pisa via Diotisalvi 2 -- 56126 PISAIl seguente proceeding si propone di discutere gli aspetti fisici di un sistema costituito da particelle cariche, massive e non relativistiche, quali sorgenti in moto di un campo elettromagnetico (e.m.) che si propaga nello spazio, riempito da un mezzo materiale lineare, omogeneo ed isotropo. Viene studiato il legame fisico tra la conservazione della quantità di moto (q.d.m.) totale e la solenoidalità per il campo di induzione magnetica. Questo studio presenta un nuovo contesto in cui la condizione necessaria per la divergenza nulla dell'induzione magnetica nell'intero spazio, nota come condizione di solenoidalità, deriva direttamente dalla conservazione della q.d.m. totale del sistema, cioè sorgenti più campo. Il lavoro, in generale, giunge a risultati che lasciano alcuni quesiti aperti sull'esistenza, o quantomeno l'osservabilità, dei monopoli magnetici, teoricamente plausibile unicamente sotto opportune ipotesi di simmetria, che, a parere degli autori, potrebbero comunque costituire un interessante argomento di discussione scientifica soprattutto nell' ambito della fisica sperimentale.298 1345 - PublicationRestrictedCoherent control of stimulated emission inside one dimensional photonic crystals: strong coupling regime(2009-06-16)
; ; ; ; ; ; ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Severini, S.; Centro Interforze Studi Applicazioni Militari (CISAM), Via della Bigattiera 10, 56122 San Piero a Grado, Pisa, Italy ;Sibilia, C.; Dipartimento di Energetica, Universit`a “La Sapienza” di Roma, via Scarpa 16, 00161 Roma, Italy ;Bertolotti, M.; Dipartimento di Energetica, Universit`a “La Sapienza” di Roma, via Scarpa 16, 00161 Roma, Italy ;Napoli, A.; Dipartimento di Scienze Fisiche ed Astronomiche, Universit`a di Palermo, via Archirafi 36, 90123 Palermo, Italy ;Messina, A.; Dipartimento di Scienze Fisiche ed Astronomiche, Universit`a di Palermo, via Archirafi 36, 90123 Palermo, Italy; ; ; ; ; The present paper discusses the stimulated emission, in strong coupling regime, of an atom embedded inside a one dimensional (1D) Photonic Band Gap (PBG) cavity which is pumped by two counter-propagating laser beams. Quantum electrodynamics is applied to model the atom-field interaction, by considering the atom as a two level system, the e.m. field as a superposition of normal modes, the coupling in dipole approximation, and the equations of motion in Wigner-Weisskopf and rotating wave approximations. In addition, the Quasi Normal Mode (QNM) approach for an open cavity is adopted, interpreting the local density of states (LDOS) as the local density of probability to excite one QNM of the cavity; and therefore rendering this LDOS dependent on the phase difference of the two laser beams. In this paper we demonstrate that the strong coupling regime occurs at high values of the LDOS. In accordance with the results of the literature, the emission probability of the atom decays with an oscillatory behaviour, so that the atomic emission spectrum exhibits two peaks (Rabi splitting). The novelty of this work is that the phase difference of the two laser beams can produce a coherent control of both the oscillations for the atomic emission probability and, as a consequence, of the Rabi splitting in the emission spectrum. Possible criteria to design active delay lines are finally discussed.350 25 - PublicationRestrictedSOLENOIDALITY OF A MAGNETIC INDUCTION FIELD AND CONSERVATION OF TOTAL MOMENTUM(INTERSCIENZE Srl, 2012-05-02)
; ; ;Severini, S.; Centro Interforze Studi per le Applicazioni Militari (CISAM), Via della Bigattiera lato monte 10, 56122 San Piero a Grado, Pisa, Italy ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; ; ; ;Amoroso, Angelo; INTERSCIENZE Srl, Via Felice Casati 7/9, 20124 Milan, ItalyThe following scientific essay proposes to discuss the physical aspects of a system consisting of some non-relativistic massive charged particles, that are the sources in motion of an electromagnetic field (e.m.) propagating through the space, filled by a linear, homogeneous, and isotropic material medium. The physical link between the conservation of total momentum and the solenoidality of a magnetic induction field is investigated. After a careful review of all the more widely sustained didactic justifications for the solenoidality of magnetic induction, some properties of the Maxwell e.m. stress tensor are defined according to Minkowski. This study presents a new framework wherein the necessary condition for the free-divergence of magnetic induction in the entire space, here named as solenoidality condition, derives directly from the total momentum conservation of the system, i.e. sources plus field.108 30 - PublicationOpen AccessSolenoidality of a magnetic induction field and conservation of total momentum(2011-09-26)
; ; ;Severini, S.; Centro Interforze Studi Applicazioni Militari (CISAM), Via della Bigattiera lato monte 10, 56122 San Piero a Grado, Pisa, Italia ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; ; ; ;Santucci, Sandro; Dipartimento di Fisica, Università dell’’Aquila.The present comunication discusses the physical aspects of a system of non-relativistic massive charge particles moving within an electromagnetic field (e.m.), which propagates through the entire space. The role of total momentum conservation on the solenoidality of a magnetic induction field is demonstrated. After a careful review of all the more widely sustained didactic justifications for the solenoidality of magnetic induction, some properties of the Maxwell stress tensor are defined according to Minkowsky. This comunication presents a new framework wherein the necessary condition for the free-divergence of induction derives directly from the total momentum conservation of the system, i.e. particles and field.232 453 - PublicationOpen AccessLinking Quasi-Normal and Natural Modes of an open cavity(2010-08-16)
; ; ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Severini, S.; Centro Interforze Studi Applicazioni Militari (CISAM) – Via della Bigattiera 10, 56122 San Piero a Grado, Pisa, Italy; The present paper proposes a comparison between the extinction theorem and the Sturm–Liouville theory approaches for calculating the electromagnetic (e.m.) field inside an optical cavity. We discuss for the first time to the best of our knowledge, in the framework of classical electrodynamics, a simple link between the quasi normal modes (QNMs) and the natural modes (NMs) for one-dimensional (1D), two-sided, open cavities. The QNM eigenfrequencies and eigenfunctions are calculated for a linear Fabry–Pe´rot (FP) cavity. The first-order Born approximation is applied to the same cavity in order to compare the first-order Born approximated and the actual QNM eigenfunctions of the cavity. We demonstrate that the first-order Born approximation for an FP cavity introduces symmetry breaking: in fact, each Born approximated QNM eigenfunction produces values below or above the actual QNM eigenfunction value on the terminal surfaces of the same cavity. Consequently, the two error-functions for an approximated QNM are not equal in proximity to the two terminal surfaces of the cavity.261 175 - PublicationOpen AccessQuasi-normal-modes description of transmission properties for photonic bandgap structures(2009-03-31)
; ; ; ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Severini, S.; Centro Interforze Studi per le Applicazioni Militari (CISAM), via della Bigattiera 10, 56010 San Pietro a Grado (Pi), Italy ;Hoenders, B. J.; Research Group Theory of Condensed Matter in the Institute for Theoretical Physics and Zernike Institute for Advanced Materials, University of Groeningen, Nijenborg 4, NL 9747 AG Groeningen, Netherlands; ; We use the “quasi-normal-modes” (QNM) approach for discussing the transmission properties of double-side opened optical cavities: in particular, this approach is specified for one-dimensional (1D) “photonic bandgap” (PBG) structures. Moreover, we conjecture that the density of the modes is a dynamical variable that has the flexibility of varying with respect to the boundary conditions as well as the initial conditions; in fact, the electromagnetic (e.m.) field generated by two monochromatic counterpropagating pump waves leads to interference effects inside a quarter-wave symmetric 1D-PBG structure. Finally, here, for the first time to the best of our knowledge, a large number of theoretical assumptions on QNM metrics for an open cavity, never discussed in literature, are proved, and a simple and direct method to calculate the QNM norm for a 1D-PBG structure is reported.471 225 - PublicationRestrictedOn the Divergenceless Property of the Magnetic Induction Field(2013-03-01)
; ; ;Severini, S.; Centro Interforze Studi per le Applicazioni Militari (CISAM), Via Bigattiera Lato Monte 10, San Piero a Grado, 56122 Pisa, Italy ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Maxwell’s equations beautifully describe the electromagnetic fields properties. In what follows we will be interested in giving a new perspective to divergence-free Maxwell’s equations regarding the magnetic induction field: divB=0. To this end we will consider some physical aspects of a system consisting of massive nonrelativistic charged articles, as sources of an electromagnetic field (e.m.) propagating in free space. In particular the link between conservation of total momentum and divergence-free condition for the magnetic induction B field will be deeply investigated.This study presents a new context in which the necessary condition for the divergence-free property of the magnetic induction field in the whole space, known as solenoidality condition, directly comes from the conservation of total momentum for the system, that is, sources and field. This work, in general, leads to results that leave some open questions on the existence, or at least the bservability, of magnetic monopoles, theoretically plausible only under suitable symmetry assumptions as we will show.282 2010